Showing papers in "Ices Journal of Marine Science in 2009"
TL;DR: Rabalais et al. as mentioned in this paper proposed that global climate changes will likely result in higher water temperatures, stronger stratification, and increased inflows of freshwater and nutrients to coastal waters in many areas of the globe.
Abstract: Rabalais, N. N., Turner, R. E., Diaz, R. J., and Justic, D. 2009. Global change and eutrophication of coastal waters. - ICES Journal of Marine Science, 66: 1528-1537.The cumulative effects of global change, including climate change, increased population, and more intense industrialization and agribusiness, will likely continue and intensify the course of eutrophication in estuarine and coastal waters. As a result, the symptoms of eutrophication, such as noxious and harmful algal blooms, reduced water quality, loss of habitat and natural resources, and severity of hypoxia (oxygen depletion) and its extent in estuaries and coastal waters will increase. Global climate changes will likely result in higher water temperatures, stronger stratification, and increased inflows of freshwater and nutrients to coastal waters in many areas of the globe. Both past experience and model forecasts suggest that these changes will result in enhanced primary production, higher phytoplankton and macroalgal standing stocks, and more frequent or severe hypoxia. The negative consequences of increased nutrient loading and stratification may be partly, but only temporarily, compensated by stronger or more frequent tropical storm activity in low and mid-latitudes. In anticipation of the negative effects of global change, nutrient loadings to coastal waters need to be reduced now, so that further water quality degradation is prevented.
899 citations
TL;DR: Available evidence suggests climate-related changes in recruitment success to be the key process, stemming from either higher production or survival in the pelagic egg or larval stage, or owing to changes in the quality/quantity of nursery habitats.
Abstract: This paper develops a framework for the study of climate on fish populations based on first principles of physiology, ecology, and available observations. Environmental variables and oceanographic features that are relevant to fish and that are likely to be affected by climate change are reviewed. Working hypotheses are derived from the differences in the expected response of different species groups. A review of published data on Northeast Atlantic fish species representing different biogeographic affinities, habitats, and body size lends support to the hypothesis that global warming results in a shift in abundance and distribution (in patterns of occurrence with latitude and depth) of fish species. Pelagic species exhibit clear changes in seasonal migration patterns related to climateinduced changes in zooplankton productivity. Lusitanian species have increased in recent decades (sprat, anchovy, and horse mackerel), especially at the northern limit of their distribution areas, while Boreal species decreased at the southern limit of their distribution range (cod and plaice), but increased at the northern limit (cod). Although the underlying mechanisms remain uncertain, available evidence suggests climate-related changes in recruitment success to be the key process, stemming from either higher production or survival in the pelagic egg or larval stage, or owing to changes in the quality/quantity of nursery habitats.
629 citations
TL;DR: In this paper, Charles et al. explored ten human dimensions that are basic to the acceptance and ultimate success of MPAs: objectives and attitudes, "entry points" for introducing MPAs, attachment to place, meaningful participation, effective governance, the "people side" of knowledge, the role of rights, concerns about displacement, MPA costs and benefits, and the bigger picture around MPAs.
Abstract: Charles, A., and Wilson, L. 2009. Human dimensions of Marine Protected Areas. - ICES Journal of Marine Science, 66: 6-15.Planning, implementing, and managing Marine Protected Areas (MPAs) requires that attention be paid not only to the biological and oceanographic issues that influence the performance of the MPA, but equally to the human dimensions: social, economic, and institutional considerations that can dramatically affect the outcome of MPA implementation. This paper explores ten human dimensions that are basic to the acceptance and ultimate success of MPAs: objectives and attitudes, “entry points” for introducing MPAs, attachment to place, meaningful participation, effective governance, the “people side” of knowledge, the role of rights, concerns about displacement, MPA costs and benefits, and the bigger picture around MPAs. These people-orientated factors and their impact on the success and effectiveness of MPAs are examined in relation to experiences with MPAs globally, and in relation to two Canadian examples specifically, one coastal (Eastport, Newfoundland) and the other offshore (the Gully, Nova Scotia).
290 citations
TL;DR: Retrospective growth analyses of eight stock/sea age components show that post-smolt growth during summer is positively correlated with salmon survival and recruitment, and the Atlantic Multidecadal Oscillation appears to be a more closely aligned climate forcing index than the North Atlantic O oscillation with respect to salmon recruitment.
Abstract: The stock complex of Atlantic salmon, Salmo salar, in Europe has experienced a multidecadal decline in recruitment, resulting in the lowest stock abundances observed since 1970. Here, physical forcing, biological interactions, and the resultant growth response of postsmolt salmon are examined with a view to understanding the mechanism controlling recruitment. Sea surface temperature (SST) has increased in the Northeast Atlantic, with the pattern and seasonal change in SST negatively correlated with post-smolt survival during summer and in a region that spatially matches the post-smolt nursery. Constituents of the pelagic foodweb, including potential postsmolt food and plankton that may affect post-smolt forage, have changed on a decadal scale and correlate with salmon survival. Retrospective growth analyses of eight stock/sea age components show that post-smolt growth during summer is positively correlated with salmon survival and recruitment. The Atlantic Multidecadal Oscillation appears to be a more closely aligned climate forcing index than the North Atlantic Oscillation with respect to salmon recruitment. European Atlantic salmon recruitment appears to be governed by factors that affect the growth of post-smolts during their first summer at sea, including SST and forage abundances; growth appears to mediate survival by the functional relationship between post-smolts and their predators.
185 citations
TL;DR: The depletion-corrected average catch (DCAC) as discussed by the authors is an extension of the potential-yield formula, and it provides useful estimates of sustainable yield for data-poor fisheries on long-lived species.
Abstract: The depletion-corrected average catch (DCAC) formula is an extension of the potential-yield formula, and it provides useful estimates of sustainable yield for data-poor fisheries on long-lived species. Over an extended period (e.g. a decade or more), the catch is divided into a sustainable yield component and an unsustainable “windfall” component associated with a one-time reduction in stock biomass. The size of the windfall is expressed as being equivalent to a number of years of sustainable production, in the form of a “windfall ratio”. The DCAC is calculated as the sum of catches divided by the sum of the number of years in the catch series and this windfall ratio. Input information includes the sum of catches and associated number of years, the relative reduction in biomass during that period, the natural mortality rate (M, which should be ,0.2 year 21 ), and the assumed ratio of FMSY to M. These input values are expected to be approximate, and based on the estimates of their imprecision, the uncertainty can be integrated by Monte Carlo exploration of DCAC values.
138 citations
TL;DR: In this paper, a long-distance, migratory seaduck was recorded using surveillance radar at a Danish offshore wind farm with emphasis placed on the 200 000+ migrating common eiders that pass through the area annually.
Abstract: Advances in technology and engineering are enhancing the contribution that wind power makes to renewable energy generation. Wind farms, both operational and in planning, can be expected to impact negatively on wildlife populations, particularly birds. We propose a novel approach to assess the impacts through the energetic costs of avoidance behaviour for a long-distance, migratory seaduck. Flight trajectories were recorded using surveillance radar at a Danish offshore wind farm with emphasis placed on the 200 000+ migrating common eiders that pass through the area annually. Minimum distance to wind farm and curvature of trajectories were compared pre- and post-construction. Additional costs of the avoidance response were estimated using an avian energetic model. The curvature of eider trajectories was greatest post-construction and within 500 m of the wind farm, with a median curvature significantly greater than pre-construction, suggesting that the birds adjusted their flight paths in the presence of the wind farm. Additional distance travelled as a consequence of the wind farm’s presence was ca. 500 m and trivial compared with the total costs of a migration episode of 1400 km. However, construction of further wind farms along the migration route could have cumulative effects on the population, especially when considered in combination with other human actions.
136 citations
TL;DR: It is concluded that offshore installations may play an important role as nocturnal porpoise-feeding stations in an overfished environment, but that further replicated and controlled studies are required.
Abstract: Todd, V. L. G., Pearse, W. D., Tregenza, N. C., Lepper, P. A., and Todd, I. B. 2009. Diel echolocation activity of harbour porpoises (Phocoena phocoena) around North Sea offshore gas installations. - ICES Journal of Marine Science, 66: 734-745.Echolocation clicks of harbour porpoises (Phocoena phocoena) were detected with T-PODs, autonomous, passive, acoustic-monitoring devices, deployed from an offshore-exploration-drilling-rig and gas-production-platform complex in the Dogger Bank region of the North Sea from 2005 to 2006. Echolocation-click trains were categorized into four phases of the diel cycle: morning, day, evening, and night. Porpoises were present near (<200 m) the platform, and there was a pronounced diel pattern in echolocation activity; the number of porpoise encounters (visits) was greater by night than by day. The number of click trains with a minimum inter-click interval of <10 ms also increased at night. This was confirmed by a comparison of the ratios of feeding buzzes to search-phase clicks (feeding buzz ratios) and an analysis of the changes in pulse-repetition frequencies within each train. A reasonable interpretation of this pattern was that porpoises were feeding below or around the platform at night. The evidence for changes in activity during the morning and evening was less clear, so these may be transitional phases. The pattern of porpoise-echolocation behaviour around this platform is related most probably to the diel activity of their prey. If porpoises cluster regularly around such installations within 500-m shipping exclusion zones, they may be omitted from population surveys. We conclude that offshore installations may play an important role as nocturnal porpoise-feeding stations in an overfished environment, but that further replicated and controlled studies are required. These findings should be taken into consideration during offshore-installation-decommissioning decisions in the North Sea.
132 citations
TL;DR: Kloser et al. as discussed by the authors demonstrated the potential and challenges of an acoustic basin-scale, fishing-vessel monitoring program, including optical and net sensing, which could assist in characterizing the biodiversity, distribution, and biomass of the micronekton fish.
Abstract: Kloser, R. J., Ryan, T. E., Young, J. W., and Lewis, M. E. 2009. Acoustic observations of micronekton fish on the scale of an ocean basin: potential and challenges. - ICES Journal of Marine Science, 66: 998-1006.Acoustic methods of characterizing micronekton communities (∼2 to 20 cm length) on the scale of an ocean basin could provide valuable inputs to ecosystem-based fishery management, marine planning, and monitoring the effects of climate change. The micronekton fish are important forage for top predators (e.g. tunas), and information on their diversity, distribution, size-structure, and abundance is needed to increase accuracy of top-predator distribution and abundance predictions. At the scale of an ocean basin, four years of Tasman Sea transects using a fishing vessel provide fine-scale maps of acoustic backscatter at 38 kHz that reveal detailed spatial patterns and structure to depths of 1200 m. Research-vessel data provide detailed biodiversity, density, size structure, and acoustic-scattering information from depth-stratified net sampling and a lowered acoustic probe. Wet-weight biomass estimates of the micronekton fish in the region vary considerably by a factor of 5-58 between acoustics (16-29 g m −2 ), nets (1.6 g m −2 ), and large spatial-scale, ecological models (0.5-3 g m −2 ). We demonstrate the potential and challenges of an acoustic basin-scale, fishing-vessel monitoring programme, including optical and net sensing, which could assist in characterizing the biodiversity, distribution, and biomass of the micronekton fish.
132 citations
TL;DR: A generalized additive model (GAM) was applied to fishery-survey data to reveal the influences of environmental factors on the distribution patterns of Japanese anchovy, sand lance, and krill and indicated non-linear responses of the two indices to the environmental covariates.
Abstract: Murase, H., Nagashima, H., Yonezaki, S., Matsukura, R., and Kitakado, T. 2009. Application of a generalized additive model (GAM) to reveal relationships between environmental factors and distributions of pelagic fish and krill: a case study in Sendai Bay, Japan. – ICES Journal of Marine Science, 66: 000–000. A generalized additive model (GAM) was applied to fishery-survey data to reveal the influences of environmental factors on the distribution patterns of Japanese anchovy (Engraulis japonicus), sand lance (Ammodytes personatus), and krill (Euphausia pacifica). Echosounder and physical-oceanographic data were collected in Sendai Bay, Japan, in spring 2005. A hierarchical model was used with two spatial strata: (i) presence and absence of each species; and (ii) biomass density of each species, given its presence; and six environmental covariates (surface water temperature, salinity, and chlorophyll, and near-seabed water temperature, salinity, and depth). The results indicate non-linear responses of the two indices to the environmental covariates. In addition, the biomasses estimated by the GAMs were comparable with estimates based on conventional, stratified-random sampling for each species. GAMs are very useful for (i) investigating the effects of environmental factors on the distributions of biological organisms, and (ii) predicting the distributions of animal densities in unsurveyed areas.
128 citations
TL;DR: Hollowed et al. as mentioned in this paper proposed a framework for modeling fish and shellfish responses to future climate change, which involves identifying mechanisms underlying the reproductive success, growth, and distribution of major fish populations, assessment of the feasibility of downscaling implications of climate scenarios derived from Intergovernmental Panel on Climate Change (IPCC) models for regional ecosystems to select and estimate relevant environmental variables, evaluation of climate model scenarios and select IPCC models that appear to provide valid representations of forcing for the region of study, extraction of environmental variables from climate scenarios and incorporation into projection models for fish and
Abstract: Hollowed, A. B., Bond, N. A., Wilderbuer, T. K., Stockhausen, W. T., A’mar, Z. T., Beamish, R. J., Overland, J. E., and Schirripa, M. J. 2009. A framework for modelling fish and shellfish responses to future climate change. – ICES Journal of Marine Science, 66: 000–000. A framework is outlined for a unified approach to forecasting the implications of climate change on production of marine fish. The framework involves five steps: (i) identification of mechanisms underlying the reproductive success, growth, and distribution of major fish and shellfish populations, (ii) assessment of the feasibility of downscaling implications of climate scenarios derived from Intergovernmental Panel on Climate Change (IPCC) models for regional ecosystems to select and estimate relevant environmental variables, (iii) evaluation of climate model scenarios and select IPCC models that appear to provide valid representations of forcing for the region of study, (iv) extraction of environmental variables from climate scenarios and incorporation into projection models for fish and shellfish, and (v) evaluation of the mean, variance, and trend in fish and shellfish production under a changing ecosystem. This framework was applied to forecast summer sea surface temperature in the Bering Sea from 2001 to 2050. The mean summer surface temperature was predicted to increase by 28C by 2050. The forecasting framework was also used to estimate the effects of climate change on production of northern rock sole (Lepidopsetta polyxystra) through projected changes in cross-shelf transport of larvae in the Bering Sea. Results suggest that climate change will lead to a modest increase in the production of strong year classes of northern rock sole.
124 citations
TL;DR: The case for MHM being incorporated as an explicit and early process following initial goal-setting within larger EBM programmes is built and issues of implicit and explicit linkages between classification, mapping, and elements of biodiversity with management goals are addressed.
Abstract: Cogan, C. B., Todd, B. J., Lawton, P., and Noji, T. T. 2009. The role of marine habitat mapping in ecosystem-based management. - ICES Journal of Marine Science, 66: 2033-2042.Ecosystem-based management (EBM) and the related concept of large marine ecosystems (LMEs) are sometimes criticized as being too broad for many management and research applications. At the same time, there is a great need to develop more effectively some substantive scientific methods to empower EBM. Marine habitat mapping (MHM) is an example of an applied set of field methods that support EBM directly and contribute essential elements for conducting integrated ecosystem assessments. This manuscript places MHM practices in context with biodiversity models and EBM. We build the case for MHM being incorporated as an explicit and early process following initial goal-setting within larger EBM programmes. Advances in MHM and EBM are dependent on evolving technological and modelling capabilities, conservation targets, and policy priorities within a spatial planning framework. In both cases, the evolving and adaptive nature of these sciences requires explicit spatial parameters, clear objectives, combinations of social and scientific considerations, and multiple parameters to assess overlapping viewpoints and ecosystem functions. To examine the commonalities between MHM and EBM, we also address issues of implicit and explicit linkages between classification, mapping, and elements of biodiversity with management goals. Policy objectives such as sustainability, ecosystem health, or the design of marine protected areas are also placed in the combined MHM-EBM context.
TL;DR: In this paper, the recruitment of North Sea herring (Clupea harengus) has been studied and it is shown that the poor recruitment arises during the larval overwintering phase, with recent survival rates greatly reduced.
Abstract: Environmentally induced change appears to be impacting the recruitment of North Sea herring (Clupea harengus). Despite simultaneously having a large adult population, historically low exploitation, and Marine Stewardship Council accreditation (implying sustainability), there have been an unprecedented 6 sequential years of poor juvenile production (recruitment). Analysis suggests that the poor recruitment arises during the larval overwintering phase, with recent survival rates greatly reduced. Contemporary warming of the North Sea has caused significant changes in the plankton community, and a recently identified regime shift around 2000 shows close temporal agreement with the reduced larval survival. It is, therefore, possible that we are observing the first consequences of this planktonic change for higher trophic levels. There is no indication of a recovery in recruitment in the short term. Fishing mortality is currently outside the agreed management plan, and forecasts show a high risk of the stock moving outside safe biological limits soon, potentially precipitating another collapse of the stock. However, bringing the realized fishing mortality back in line with the management plan would likely alleviate the problem. This illustrates again that recruitment is influenced by more than just spawning-stock biomass, and that changes in other factors can be of equal, or even greater, importance. In such dynamically changing environments, recent management success does not necessarily guarantee future sustainability.
Abstract: Churnside, J. H., and Donaghay, P. L. 2009. Thin scattering layers observed by airborne lidar. - ICES Journal of Marine Science, 66: 778-789.More than 2000 km of thin (<3 m) optical scattering layers were identified in 80 000 km of airborne lidar data collected from a variety of oceanic and coastal waters. The spatial characteristics of thin layers varied dramatically from (i) those that were self-contained features consistently <3-4 m thick over their 1-12 km extent to (ii) those that were clearly parts of much longer layers that had gaps and/or regions where the layer became more intense and much thicker than the 3-m criterion. The characteristics of the lidar signal suggest that plankton was the most likely source of scattering. Examples from upwelling regions, areas with large fresh-water influx, and warm-core eddies are presented. The results are quite consistent with the characteristics observed in studies of thin plankton layers in fjords and near-coastal waters. These layers exhibit great spatial variability that is difficult to observe using traditional methods, and examples of layer perturbations by both linear and non-linear internal waves are presented. The results suggest that airborne lidar can be a powerful tool not only for detecting and mapping the spatial extent of thin scattering layers and linking their occurrence to larger scale physical processes, but also for tracking their evolution over time and guiding the ship-based sampling needed to understand their composition, dynamics, and impacts. Such a capability will be crucial in future studies designed to test the hypothesis that thin plankton layers have the spatial extent and intensity to play a key role in controlling the recruitment of fish larvae, biogeochemical cycling, trophic transfer processes, plankton biodiversity, and harmful algal bloom dynamics.
TL;DR: In this article, the capacity of X-11 to capture interannual variations in seasonality is used to diagnose the stability of the Chl a seasonal cycle, and linear changes in Chl A concentration observed after a decade of continuous ocean colour record agree globally with previous observations on shorter series.
Abstract: to 64% of the total variance, compared with only 36% if a fixed annual cycle is assumed. The capacity of X-11 to capture interannual variations in seasonality is used to diagnose the stability of the Chl a seasonal cycle. Finally, linear changes in Chl a concentration observed after a decade of continuous ocean colour record agree globally with previous observations on shorter series. Significant changes of both signs are detected in various regions of the world’s oceans, but primarily a general decrease of Chl a in the mid-ocean gyres.
TL;DR: In this article, the authors studied diver underwater behaviour, the effects on the natural environment, and the characteristics that may influence diver behaviour, and found that flapping was the most frequent type of contact with the seabed and the main damage by this action was to raise sediment.
Abstract: The features of many Marine Protected Areas (MPAs) have increased scuba diving tourism in these areas. Impacts caused by recreational scuba activity vary widely among different divers with differing underwater behaviour. We studied diver underwater behaviour, the effects on the natural environment, and the characteristics that may influence diver behaviour. In all, 181 recreational divers were followed, and contacts and the effects produced were recorded. Information on diver profile and dive features was recorded. Field sampling revealed that 175 of the divers observed (96.7%) made at least one contact with the seabed, with a mean contact of 41.20+ 3.55 (mean+ s.e.) per diver per 10 min. Flapping was the most frequent type of contact, and the main damage by this action was to raise sediment. Contact with the seabed was greater for males than for females, inexperienced divers than for experienced divers, camera or lantern (dive light) users than for non-users, and divers unaccompanied by a dive leader or who had not been briefed about avoiding seabed contact before undertaking a dive than for accompanied or briefed divers. A greater understanding of the causes of harmful behaviour may be useful for stricter management, reducing diving damage and assuring the sustainability of this activity in MPAs.
TL;DR: In this article, the authors used simulation testing with feedback to examine the robustness of candidate management strategies to error and uncertainty in a fishery for walleye pollock in the Gulf of Alaska (GOA).
Abstract: Management strategy evaluation (MSE) is the process of using simulation testing with feedback to examine the robustness of candidate management strategies to error and uncertainty. The structure of the management strategy can be selected to attempt to satisfy desired (but conflicting) management objectives. MSE was used to assess the performance of the current management strategy and an alternative management strategy (the “dynamic B0” strategy) for the fishery for walleye pollock (Theragra chalcogramma) in the Gulf of Alaska (GOA), when age-1 recruitment was driven by climate. The relationships between age-1 abundance and climate indices (and the uncertainties associated with these relationships) were characterized within an age-structured operating model that was fitted to the data for GOA walleye pollock. Projections into the future were based on the fitted relationships and predictions of those indices from the Intergovernmental Panel on Climate Change (IPCC) models, using the current or the alternative management strategy to determine catch limits. Management performance (the ability to leave the stock close to the management reference level and achieve high and stable catches) deteriorated when age-1 recruitment was forced by climate, although stocks were kept near the reference level on average. In addition, the ability to estimate management-related quantities, such as spawning biomass, deteriorated markedly when recruitment was forced by climate. Performance was sensitive to the choice of IPCC dataset and, in particular, estimation and management performance was poorest (outcomes most variable) for the IPCC datasets that led to the greatest variation in recruitment to the fishery. Although basing management on a “dynamic B0” management strategy led to improved management and estimation performance, the magnitude of the improvement was slight.
TL;DR: The relationship between the observed water mass properties and the winter North Atlantic Oscillation (NAO) index (1950-2000s; r 2 � 0.65) implies that changes in the NAO-related atmospheric forcing may account for up to two-thirds of thermohaline changes at the intermediate and deep levels in the subpolar North Atlantic on a decadal time-scale as mentioned in this paper.
Abstract: The close relationship between the observed water mass properties and the winter North Atlantic Oscillation (NAO) index (1950 – 2000s; r 2 � 0.65) implies that changes in the NAO-related atmospheric forcing may account for up to two-thirds of thermohaline changes at the intermediate and deep levels in the subpolar North Atlantic on a decadal time-scale. Persistent NAO decline (amplification) results in increase (decrease) in temperature and salinity in the intermediate –deep water column. A general mechanism explaining the close link between the NAO and coherent decadal changes in the intermediate and deep-water temperature and salinity in the region is inferred from the observed changes in the regional circulation and water mass properties. Two factors dominate this link: (i) intensity of convection in the Labrador Sea controlling injection of relatively cold freshwater into the intermediate layer, and (ii) zonal extension of the Subpolar Gyre that regulates the relative contribution of cold fresh subpolar water and warm saline subtropical water to the deep-water formation.
TL;DR: Overall abundance for many of the species examined was 2 – 3 times higher on the complex artificial habitats than on simple artificial or natural reef habitats, suggesting enhanced habitat availability produced by the increased structural complexity delivered through specifically designed artificial reefs may have the potential to augment faunal abundance while promoting species diversity.
Abstract: Several north temperate marine species were recorded on subtidal hard-substratum reef sites selected to produce a gradient of structural complexity. The study employed an established scuba-based census method, the belt transect. The three types of reef examined, with a measured gradient of increasing structural complexity, were natural rocky reef, artificial reef constructed of solid concrete blocks, and artificial reef made of concrete blocks with voids. Surveys were undertaken monthly over a calendar year using randomly placed fixed rope transects. For a number of conspicuous species of fish and invertebrates, significant differences were found between the levels of habitat complexity and abundance. Overall abundance for many of the species examined was 2 – 3 times higher on the complex artificial habitats than on simple artificial or natural reef habitats. The enhanced habitat availability produced by the increased structural complexity delivered through specifically designed artificial reefs may have the potential to augment faunal abundance while promoting species diversity.
TL;DR: Williams et al. as discussed by the authors evaluated the interaction between two hierarchical levels (depth and geomorphic features), using video survey data on seamounts and submarine canyons, and found that false within-class homogeneity indicated that depth, size, complexity, configuration, and anthropogenic impact need to be added as modifiers to allow geomorphic feature to act as surrogates for biodiversity distribution.
Abstract: Williams, A., Bax, N. J., Kloser, R. J., Althaus, F., Barker, B., and Keith G. 2009. Australia’s deep-water reserve network: implications of false homogeneity for classifying abiotic surrogates of biodiversity. - ICES Journal of Marine Science, 66: 214-224.Australia’s southeast network of deep-water marine reserves, declared in July 2007, was designed using a hierarchy that represented the distribution of marine biodiversity as a nested set of bioregions. In this hierarchy, geomorphic units, individual or aggregations of seabed geomorphic features, are the finest scale used in the design process. We evaluated the interaction between two hierarchical levels (depth and geomorphic features), using video survey data on seamounts and submarine canyons. False within-class homogeneity indicated that depth, size, complexity, configuration, and anthropogenic impact need to be added as modifiers to allow geomorphic features to act as surrogates for biodiversity distribution. A consequence of using unmodified geomorphic surrogates, and of not correctly nesting geomorphic features within depth, is the diminished recognition of the importance and comparative rarity of megafaunal biodiversity of the continental margin (<1500-m depths). We call this area the zone of importance, because it is where targeted marine impacts coincide with the greatest megafaunal biodiversity. Refining the geomorphic classification is desirable for future biodiversity characterization, but an alternative approach is to define patterns in biodiversity and abiotic variables jointly, and to utilize finer scale information and provide a classification that preserves the maximum information of both datasets.
TL;DR: Koslow et al. as discussed by the authors discussed the role of acoustics in ecosystem-based fishery management, and the potential effects of climate variability and climate change on recruitment.
Abstract: Koslow, J. A. 2009. The role of acoustics in ecosystem-based fishery management. - ICES Journal of Marine Science, 66: 966-973.For more than half a century, acoustics has been a leading tool in fishery stock assessment. Today, the need for ecosystem-based management poses new challenges for fishery scientists: the need to assess the ecological relationships of exploited species with predators and prey and to predict the potential effects of climate variability and climate change on recruitment. No research tool is likely to prove as effective as acoustics in meeting these needs, if it is properly integrated into interdisciplinary research programmes involving ecology and oceanography, as well as fisheries. Integration of data from acoustics and ocean-observation, as well as from satellites and other high-resolution oceanographic mapping tools, is likely to lead to major advances in fishery oceanography. New developments in acoustic technology, such as three-dimensional, multibeam acoustics, and shelf-scale acoustic mapping, may also lead to significant advances. Notwithstanding these developments, critical biases and shortcomings of acoustic methods that were noted 50 years ago remain with us. For example, the identification of insonified biota and single-target discrimination remains relatively primitive. Progress is urgently needed in these basic underpinnings of the acoustic method.
TL;DR: In this article, the authors present a set of recommendations that use in situ target strength (TS) to scale volume backscattering in the Laurentian Great Lakes and Lake Champlain.
Abstract: Acoustic surveys are conducted annually in all five of the Laurentian Great Lakes and Lake Champlain to assess forage-fish abundance. The main target species are rainbow smelt (Osmerus mordax), alewife (Alosa pseudoharengus), and several coregonine species (Coregonus spp.). The Great Lakes Fishery Commission sponsored an Acoustic Study Group from 2002 to 2006 to discuss common problems and suggest standardized methods across these lakes. The study group produced a set of recommendations, available as a Great Lakes Fishery Commission Special Publication and on the web, that use in situ target strength (TS) to scale volume backscattering. Here, we review these recommendations with special attention to four often-overlooked topics of interest to all acoustic users, namely issues associated with first, the choice of thresholds for both TS and volume-backscattering strength, second, different settings for single-echo detection algorithms for measures of in situ TS, third, those taking account of measuring in situ TS in dense fish concentrations, and finally, detection limits.
TL;DR: Coelho et al. as mentioned in this paper applied a numerical model to a stretch of the Portuguese coast to determine the effects of various scenarios of wave action and sea level rise (SLR) that might result from climate change over the next 25 years.
Abstract: Coelho, C., Silva, R., Veloso-Gomes, F., and Taveira-Pinto, F. 2009. Potential effects of climate change on northwest Portuguese coastal zones. - ICES Journal of Marine Science, 66: 1497-1507.Coastal erosion is a common problem in Europe; a result of the dynamic nature of its coastal zones, of anthropogenic influences, such as coastal interventions and littoral occupation, and of the effects of climate change. The increase in the occurrence of extreme events, the weakening of river-sediment supplies, and the general acceleration of sea level rise (SLR) probably tends to aggravate coastal erosion on decadal time-scales. Describing vulnerability and risk patterns for energetic environmental actions is important for coastal planning and management to rationalize the decision-making process. To minimize negative effects, the various processes causing erosion must be understood to assess the possible prediction scenarios for coastal evolution in the medium to long term. This paper describes the application of a coastal (shoreline evolution) numerical model to a stretch of the Portuguese coast to determine the effects of various scenarios of wave action and SLR that might result from climate change over the next 25 years. We conclude that the effects of SLR are less important than changes in wave action. The numerical model was also applied in a generic situation to compare shoreline evolution with and without anthropogenic intervention.
TL;DR: Korneliussen et al. as discussed by the authors used the relative frequency response (r(f) measured simultaneously at several frequencies) to identify schooling fish with similar acoustic properties, although the results have limited spatial resolution.
Abstract: Korneliussen, R. J., Heggelund, Y., Eliassen, I. K., and Johansen, G. O. 2009. Acoustic species identification of schooling fish. - ICES Journal of Marine Science, 66: 1111-1118.The development of methods for the acoustic identification of fish is a long-term objective aimed at reducing uncertainty in acoustic-survey estimates. The relative frequency response r(f) measured simultaneously at several frequencies is one of the main acoustic features that characterize the targets, but the relationship between nearest neighbours, school morphology, and environmental and geographical data are also important characteristics in this context. The number of acoustic categories that can be separated with a high spatial resolution is limited by the stochastic nature of the measurements. Because the acoustic categorization of larger ensembles is more reliable than for single targets, spatial smoothing of the backscattering within the school boundaries before that process allows the separation of more categories than is possible with the raw, highly resolved data. Using the mean r(f) of an entire school gives even more reliable categorization, but determining whether or not the school is monospecific sets a new challenge. This problem is evaluated here. The methods are tested and verified. Identification of acoustic categories with similar acoustic properties is done for schooling fish, although the results have limited spatial resolution. The reliability of the categorization is further improved when knowledge of school morphology and geographical distribution of the species are taken into account.
TL;DR: In this article, the long-term management of a stock representing a metapopulation was simulated in a case study loosely based upon herring to the west of the British isles, where stocks are currently assessed and managed by management area, although there is evidence of mixing between stocks (in terms of connectivity, migrations, and exploitation).
Abstract: The long-term management of a stock representing a metapopulation has been simulated in a case study loosely based upon herring to the west of the British isles, where stocks are currently assessed and managed by management area, although there is evidence of mixing between stocks (in terms of connectivity, migrations, and exploitation). The simulations evaluate scientific advice (based on virtual population analysis, VPA) and the sustainability of fishing under two population-structure scenarios, corresponding either to discrete stocks, which only mix on the feeding grounds, or where diffusion between stocks takes place. The ability of stock assessment to monitor stock status and exploitation levels was evaluated for defining stocks based on fishing areas and for stocks that combined fishing areas. The study showed that assessment based on VPA of the metapopulation could fail to detect overexploitation of stocks and fail to detect and distinguish between the effects of exploitation and regime shifts
TL;DR: Mantyniemi et al. as discussed by the authors take a decision theoretical approach to fisheries management, using a Bayesian approach to integrate the uncertainty about stock dynamics and current stock status, and express management objectives in the form of a utility function.
Abstract: Mantyniemi, S., Kuikka, S., Rahikainen, M., Kell, L. T., and Kaitala, V. 2009. The value of information in fisheries management: North Sea herring as an example. - ICES Journal of Marine Science, 66: 2278-2283.We take a decision theoretical approach to fisheries management, using a Bayesian approach to integrate the uncertainty about stock dynamics and current stock status, and express management objectives in the form of a utility function. The value of new information, potentially resulting in new control measures, is high if the information is expected to help in differentiating between the expected consequences of alternative management actions. Conversely, the value of new information is low if there is already great certainty about the state and dynamics of the stock and/or if there is only a small difference between the utility attached to different potential outcomes of the alternative management action. The approach can, therefore, help when deciding on the allocation of resources between obtaining new information and improving management actions. In our example, we evaluate the value of obtaining hypothetically perfect knowledge of the type of stock-recruitment function of the North Sea herring (Clupea harengus) population.
TL;DR: A simple, spatially explicit dynamic population model was developed and confirmed previous results: closed areas do not improve the yield of populations that are optimally managed or underexploited and, as mobility increases, optimum closure size increases.
Abstract: Le Quesne, W. J. F., and Codling, E. A. 2009. Managing mobile species with MPAs: the effects of mobility, larval dispersal, and fishing mortality on closure size. - ICES Journal of Marine Science, 66: 122-131.The use of closed areas (marine protected areas, marine reserves, no-take zones) has been suggested as a possible solution to the perceived global fisheries crisis. However, to optimize the design and evaluate the effectiveness of closed areas, we need to understand the interaction between larval dispersal, adult mobility, and fishing mortality. In this paper, a simple, spatially explicit dynamic population model was developed to examine the effects of these interacting factors on optimal closure size and resulting yields. The effect of using one large or several smaller closed areas was also examined. Our model confirmed previous results: closed areas do not improve the yield of populations that are optimally managed or underexploited and, as mobility increases, optimum closure size increases. The model also predicted some interesting counter-intuitive results; for overexploited stocks, the greatest benefit from closed areas can be obtained for stocks with highest mobility, although this may require closure of 85% of the total area. For the tested parameter settings, adult spillover had greater potential to improve yield than larval export, and using several small closed areas rather than a single larger one had the same effect as increasing the mobility of the population.
TL;DR: Developments in physiological research have revealed that herring are not “primitive”, as once believed, but highly adaptable in their nutrition and metabolism, and these advances fundamentally changed the authors' view of herring.
Abstract: Geffen, A. J. 2009. Advances in herring biology: from simple to complex, coping with plasticity and adaptability. - ICES Journal of Marine Science, 66: 1688-1695.At least two centuries of investigations on herring have been absorbed by scientific journals, and applied and basic research has produced groundbreaking concepts in fisheries, population biology, and marine ecology. By the 1970s, a firm understanding of herring biology formed the basis for more sophisticated research. At that point, herring populations had been delineated, and their migration patterns described. The reproduction and early stage biology were characterized in ways that could be applied to fisheries management. However, over the subsequent four decades, new approaches and technology overturned many of the earlier findings. Behavioural studies revealed a repertoire of patterns that extended the concept of schooling, and genetic analyses showed high levels of stock mixing. Application of otolith analysis to larval, juvenile, and adult fish revealed the scope of plasticity in growth and life-history strategies. Developments in physiological research have revealed that herring are not “primitive”, as once believed, but highly adaptable in their nutrition and metabolism. These advances fundamentally changed our view of herring, and the resulting challenge is to synthesize current knowledge to help explain the significance of adaptability and plasticity in its flexible life history.
TL;DR: Mortensen et al. as discussed by the authors used a combination of multivariate analysis and GIS classification to predict benthic biotopes on a Norwegian offshore bank, which is part of the multidisciplinary seabed mapping programme MAREANO (Marine AREAdatabase for NOrwegian coast and sea areas).
Abstract: Mortensen, P. B., Dolan, M., and Buhl-Mortensen, L. 2009. Prediction of benthic biotopes on a Norwegian offshore bank using a combination of multivariate analysis and GIS classification. - ICES Journal of Marine Science, 66: 2026-2032.This study is part of the multidisciplinary seabed mapping programme MAREANO (Marine AREAdatabase for NOrwegian coast and sea areas). The mapping programme includes acquisition of multibeam bathymetry and acoustic backscatter data together with a comprehensive, integrated biological and geological sampling programme. The equipment used includes underwater video, boxcorer, grab, hyperbenthic sled, and beam trawl. The Tromsoflaket offshore bank was used as a case-study area to develop suitable methods for mapping habitats and biotopes. A procedure for producing maps of predicted biotopes is described that combined information on the distribution of biological communities with environmental factors and indicators. Detrended correspondence analysis (DCA) was used to relate bottom environment [including multiscale physical descriptors of the seabed derived from multibeam echosounder (MBES) data] and faunal distribution to find the best physical biotope descriptors. DCA of 252 video samples (sequences 200 m long) revealed six groups of locations representing different biotopes. These were characterized by different compositions of species, substrata, depths, and values for terrain parameters. Prediction of biotope distribution was performed using a supervised GIS classification with the MBES-derived physical seabed descriptors with the strongest explanatory ability (depth, backscatter, and broad-scale bathymetric position index) identified by the DCA. The species diversity of the identified biotopes was described from the content of the bottom samples. For future MAREANO cruises, an important task will be to ground-truth predictions of habitat and biotopes and to test the reliability of these predictions in the wider MAREANO area.
TL;DR: Abdulla et al. as mentioned in this paper identified several obstacles to Mediterranean MPA implementation and discuss how they can be overcome through strategic MPA network planning, contending that regional disparities in governance, institutional structures, wealth distribution, social capital, and availability of ecological data are responsible for discrepancies in the establishment and effectiveness of MPAs in this region.
Abstract: Abdulla, A., Gomei, M., Hyrenbach, D., Notarbartolo-di-Sciara, G., and Agardy, T. 2009. Challenges facing a network of representative marine protected areas in the Mediterranean: prioritizing the protection of underrepresented habitats. - ICES Journal of Marine Science, 66: 22-28.The high endemism of the Mediterranean Sea provides strong motivation to develop a comprehensive plan for the conservation of its biodiversity and the management of its marine resources. Increasingly, this ecosystem-level approach calls for a comprehensive network of marine protected areas (MPAs) representative of the richness and diversity of this shared basin. Today, Mediterranean MPAs do not represent the diverse geography and habitats in the region. Despite a recent declaration on trawling restrictions in deep waters (>1000 m), there are no true deep-sea Mediterranean MPAs. All but one (98.9%) of the 94 marine areas currently under some type of protection or management are coastal. Moreover, 69 (73.4%) are located along the basin's northern shore, highlighting the lack of MPAs in the south and east coasts. Yet, these underrepresented regions and habitats are ecologically distinctive by virtue of their particular oceanographic and biogeographic conditions. We identify several obstacles to Mediterranean MPA implementation and discuss how they can be overcome through strategic MPA network planning, contending that regional disparities in governance, institutional structures, wealth distribution, social capital, and availability of ecological data are responsible for discrepancies in the establishment and effectiveness of MPAs in this region.
TL;DR: Simulation scenarios of straying and entrainment were developed to examine the effects of component interchange and recruitment covariance on metapopulation attributes, and high rates of connectivity tended to result in increased synchronous responses between components and depressed metAPopulation productivity, stability, and PE.
Abstract: Secor, D. H., Kerr, L. A., and Cadrin, S. X. 2009. Connectivity effects on productivity, stability, and persistence in a herring metapopulation model. - ICES Journal of Marine Science, 66: 1726-1732.Diverse and interacting spawning groups of Atlantic herring (Clupea harengus) have varying degrees of independence to environmental conditions. How these population components respond independently to the same set of environmental conditions, and are connected through straying or entrainment, will contribute to the aggregate metapopulation dynamics. The consequences of connectivity for productivity, stability, and persistence were evaluated in an age-structured model of a two-component metapopulation. Simulation scenarios of straying and entrainment were developed to examine the effects of component interchange and recruitment covariance on metapopulation attributes. Asynchronous component responses should result in reduced variance in metapopulation dynamics, which was measured as the portfolio effect (PE). Most types and magnitudes of connectivity reduced metapopulation productivity and stability. Increased connectivity tended to increase instability of a component by distributing the effect of strong year classes among components and disrupting the “storage effect” within components. Density-dependent straying and entrainment, respectively, showed stabilizing and destabilizing feedback cycles on metapopulation stability and persistence. Furthermore, high rates of connectivity tended to result in increased synchronous responses between components and depressed metapopulation productivity, stability, and PE. Exploitation on a metapopulation should similarly depress independence among components because high mortality will dampen component responses to environmental forcing.