Showing papers by "David Welch published in 2015"

Ocean's eleven: a critical evaluation of the role of population, evolutionary and molecular genetics in the management of wild fisheries

Abstract: Significant changes have occurred in the well-established partnership between fisheries managers and geneticists over the last 50 years. It is therefore timely to review and recalibrate the ways in which genetic technologies can assist the fishing industry to maintain productive and sustainable harvests. Our objective is to contribute to the mutual understanding of all stakeholders in the genetics–management partnership. Genetic technologies that are relevant to fisheries management are grouped into eleven themes, which are described in plain language for a non-specialist audience. The role that the genetic information plays in fisheries management is explained, along with an assessment of the challenges and barriers that may be preventing the uptake of the information into the fisheries management process. The compelling conclusion is that genetics offers a diverse collection of versatile and useful tools for informing fisheries managers about issues that have a biological basis. Presently, mainstream use of genetic tools focuses on a narrow set of fisheries management issues, but the diversity of genetic tools and the novel issues they can address indicates that uptake will grow, particularly as communication between geneticists and end-users improves.

Variability in Migration Routes Influences Early Marine Survival of Juvenile Salmon Smolts

Abstract: Variability in animal migratory behavior is expected to influence fitness, but few empirical examples demonstrating this relationship exist. The initial marine phase in the migration of juvenile salmon smolts has been identified as a potentially critical life history stage to overall population productivity, yet how fine-scale migration routes may influence survival are unknown. Large-scale acoustic telemetry studies have estimated survival rates of outmigrant Pacific salmon smolts through the Strait of Georgia (SOG) along the British Columbian coastline to the Pacific Ocean, but these data have not been used to identify and characterize fine-scale movements. Data collected on over 850 sockeye salmon (Oncorhynchus nerka) and steelhead (Oncorhynchus mykiss) smolts detected at an array in the Strait of Georgia in 2004–2008 and 2010–2013 were analyzed to characterize migration routes and link movements to subsequent survival at an array 250 km further along the marine migration pathway. Both species exhibited disproportionate use of the most eastern route in the Strait of Georgia (Malaspina Strait). While many smolts moved across the northern Strait of Georgia acoustic array with no indication of long-term milling or large-scale east-to-west movements, large proportions (20–40% of sockeye and 30–50% of steelhead) exhibited a different behavior, apparently moving in a westward or counterclockwise pattern. Variability in migratory behavior for both species was linked to subsequent survival through the Strait of Georgia. Survival for both species was influenced by initial east-to-west location, and sockeye were further influenced by migration timing and duration of time spent near the northern Strait of Georgia array. Westward movements result in a net transport of smolts from Malaspina Strait to the Strait of Georgia, particularly for steelhead. Counterclockwise movements may be due to the currents in this area during the time of outmigration, and the higher proportion of steelhead smolts exhibiting this counterclockwise behavior may reflect a greater exposure to wind-altered currents for the more surface-oriented steelhead. Our results provide an empirical example of how movements can affect migration survival, for which examples remain rare in movement ecology, confirming that variability in movements themselves are an important part of the migratory process.

The negative affect hypothesis of noise sensitivity

Abstract: Some studies indicate that noise sensitivity is explained by negative affect, a dispositional tendency to negatively evaluate situations and the self. Individuals high in such traits may report a greater sensitivity to other sensory stimuli, such as smell, bright light and pain. However, research investigating the relationship between noise sensitivity and sensitivity to stimuli associated with other sensory modalities has not always supported the notion of a common underlying trait, such as negative affect, driving them. Additionally, other explanations of noise sensitivity based on cognitive processes have existed in the clinical literature for over 50 years. Here, we report on secondary analyses of pre-existing laboratory (n = 74) and epidemiological (n = 1005) data focusing on the relationship between noise sensitivity to and annoyance with a variety of olfactory-related stimuli. In the first study a correlational design examined the relationships between noise sensitivity, noise annoyance, and perceptual ratings of 16 odors. The second study sought differences between mean noise and air pollution annoyance scores across noise sensitivity categories. Results from both analyses failed to support the notion that, by itself, negative affectivity explains sensitivity to noise.

Cortical encoding of speech acoustics: Effects of noise and amplification.

Abstract: Objective: To investigate speech stimuli and background-noise-dependent changes in cortical auditory-evoked potentials (CAEPs) in unaided and aided conditions, and determine amplification effects on CAEPs. Design: CAEPs to naturally produced syllables in quiet and in multi-talker babble were recorded, with and without a hearing aid in the right ear. At least 300 artifact-free trials for each participant were required to measure latencies and amplitudes of CAEPs. Acoustic characteristics of the hearing-aid-transduced stimuli were measured using in-the-canal probe microphone measurements to determine unaided versus aided SNR and to compare stimulus acoustic characteristics to CAEP findings. Study sample: Ten participants with normal hearing, aged 19 to 35 years. Results: CAEP latencies and amplitudes showed significant effects of speech contrast, background noise, and amplification. N1 and P2 components varied differently across conditions. In general, cortical processing in noise was influenced by ...

Collaborative approaches to accessing and utilising historical citizen science data: a case-study with spearfishers from eastern Australia

Abstract: Scientists are increasingly utilising non-traditional data to assist with defining biological baselines and for monitoring environmental change. These data present challenges not encountered with traditional, fit-for-purpose scientific data, including engaging with data owners, building trust and maintaining relationships, analysing and interpreting data collected under varying methodologies, and the possibility that data may not suit an intended purpose. Here we describe engagement activities undertaken with recreational spearfishers to collate and examine spearfishing club data collected from competitions held throughout south-eastern Australia from the 1960s until the present, representing one of the most extensive citizen science datasets for marine species in the region. The data proved suitable for demonstrating change in coastal fish communities, some of which were consistent with expectations given a warming climate over the period considered. With an attitudinal survey of divers we also asked about their experience of environmental change, and interaction with management over recent decades. Mutually beneficial outcomes include: collating and archiving significant data that may otherwise have been lost; improved understanding of spearfisher concerns and experiences; improved engagement between collaborators; and recognition of spearfishers' desire for better engagement in science and management. Lessons learnt may be broadly applicable to improving collaboration between recreational fishers, citizen science groups, researchers and managers.

Environmental conditions and physiological state influence estuarine movements of homing sockeye salmon

Abstract: The reproductive migration of anadromous salmonids through estuarine waters is one of the most challenging stages of their life cycle, yet little is known about the environmental and physiological conditions that influence migratory behaviour. We captured, sampled tissues, tagged and released 365 sockeye salmon (Oncorhynchus nerka) homing through inner coastal waters towards the Fraser River, British Columbia, Canada. Biotelemetry was used to assess the behaviour of individual sockeye salmon approaching estuarine waters and at river entry, which were related to both fish physiological condition at release and to prevailing environmental conditions. Sockeye salmon tended to stay close to the shore, migrated during the day, and movements were related to tide. Sockeye salmon migration rate was linked to wind-induced currents, salinity and an individual's physiological state, but these factors were specific to location and stock. We propose that wind-induced currents exposed sockeye salmon entering the estuary to stronger olfactory cues associated with Fraser River water, which in turn resulted in faster migration rates presumably due to either an increased ability for olfactory navigation and/or advanced reproductive schedule through a neuroendocrine response to olfactory cues. However, once the migration had progressed further into more concentrated freshwater of the river plume, sockeye salmon presumably used wind-induced currents to aid in movements towards the river, which may be associated with energy conservation. Results from this study improve our biological understanding of the movements of Fraser River sockeye salmon and are also broadly relevant to other anadromous salmonids homing in marine environments.

Persistence of Carex bigelowii–Racomitrium lanuginosum moss heath under sheep grazing in the Grampian Mountains, Scotland

Abstract: Carex bigelowii–Racomitrium lanuginosum moss heath has been monitored on the summit of Glas Maol, Grampian Mountains, Scotland since 1990 to assess the impact of herbivores and snow-lie. This vegetation community has high conservation value in Britain, being near-natural and the habitat of some rare arctic-alpine birds. In recent decades, it has decreased in extent in British uplands, and changed in composition due to declining Racomitrium cover, with the main drivers believed to be heavy grazing and nitrogen deposition. Permanent plots were established for the monitoring, laid out at fixed distances from a ski corridor built in 1986. Sheep grazing was assessed by pellet-group counts, and botanical composition by point-quadrat analysis. Monitoring was in summer annually between 1990 and 1996, but less frequently since. The moss heath was found to retain its main characteristics from 1990 to 2008/09, with Carex bigelowii Torr. ex Schwein dominant and Racomitrium lanuginosum (Hedw.) Brid. having muc...

Responsible corporate change: detecting and managing employee stress

Abstract: Background All 120 health and safety inspectors employed by the New Zealand regulatory agency had their jobs disestablished during a restructuring process and were required to undergo an assessment process with tight time frames. Aims To report on psychological morbidity during the transition to change. Methods The Hospital Anxiety and Depression Scale (HADS) questionnaire was emailed to all 120 current inspectors to measure levels of anxiety (HAD-A) and depression (HAD-D). A score of 11 is indicative of a clinical disorder. Results Replies were received from 36% (43) of the inspectors. Of the 40 usable responses, 47% (19) and 55% (22), respectively, had HAD-A and HAD-D scores greater than the case cut-off. Only 28% (11) and 15% (6), respectively, had scores that would be considered normal. Conclusions The high scores evident in this sample are comparable to those found in patients with serious psychopathology. Change managers should recognize that the onus for primary prevention lies with the organization, in this case designing an assessment process that takes place over a reasonable time frame. They should also realize the requirement for the active monitoring of stress.

Response to Willette et al. (2015)

Abstract: We agree with the authors (WSV) that the environment in Cook Inlet changes in complicated ways. However, WSV’s listing of several unresolved questions (chiefly, in our view, whether the results apply to smaller fish or to very shallow inshore environments and whether the bottom depth of fish nets can be predicted with sufficient accuracy) is insufficient rationale for discounting the large potential benefits to both commercial and sport fishery sectors of using shallower nets. Our paper included an example that illustrated the likely relative harvest rates of using nets fishing at two specific depths (3.5 and 5.5 m). As we specifically noted in the caption to figure nine, we assumed net depths ‘…to be directly proportional to the number of meshes; if the effective maximum depth of the net is different (because mesh size varies or nets billow under strong tidal currents), this would amount to a lateral shift of the curves along the x-axis’. The analysis remains valid if we were to replace an assumed fixed-depth net with a variable net depth that oscillates over the tidal cycle; in this case, we would integrate the relative harvest rates of the nets as their effective depth changes over time. In practical terms, we would substitute the average effective depth of the net during that part of the tidal cycle chosen for a fishery opening and read off the relative harvest rates from the existing figure nine. It is important to remember that the current management regime in Cook Inlet is neither the result of a carefully tailored biological analysis nor one based on a careful economic analysis of what management system will provide the best economic value to the state. Rather, the current system is a set of inherited rules now nearly 50 years old that managed harvest levels adequately in an earlier time when severe conservation concerns for Chinook did not exist and which more or less satisfied the competing interests of the stakeholders. As a result, all fishing sectors could obtain satisfactory livelihoods and co-exist. Because the regulations allowed ‘co-existence,’ no one really questioned whether they were economically and biologically optimal, and there was thus little pressure to change. In our view, the advent of new information derived from telemetry technologies should allow managers to fill in key knowledge gaps and re-assess management regulations in this light. As WSV note, fisheries management in Cook Inlet has become ‘highly contentious;’ we agree, but do not agree that maintaining status quo management in the face of recent major environmental change is the best option, because major social, economic, and (possibly) biological loss is occurring. The key questions are as follows: (a) Is the existing management structure close to the best possible? and (b) If not, what steps could be taken to improve the management? Our results suggest that improvements to the management structure are indeed possible, because technological developments in acoustic telemetry provide an unprecedented ability to measure the movements of fish. The ability of properly implemented telemetry systems to identify radical alternatives to the status quo is widely underappreciated in our view, not just in Alaska but worldwide. In broad terms, our past inability to know where and how fish move has blinded us to opportunities to improve our management. In the current case, telemetry data allows us to identify a possible new regulatory solution that should improve the economic utility of both fishing sectors, a previously unrecognized possibility. Major restrictions have been imposed on the Eastside Setnet (ESSN) Fishery relative to earlier periods. These resulted in huge declines in fishing effort and revenue, which also occur at a time when the target species (sockeye) is at high levels of abundance, exacerbating