Showing papers in "Reviews in Fish Biology and Fisheries in 1999"

Cortisol in teleosts: dynamics, mechanisms of action, and metabolic regulation

Abstract: Cortisol is the principal corticosteriod in teleost fishes and its plasma concentrations rise dramatically during stress. The relationship between this cortisol increase and its metabolic consequences are subject to extensive debate. Much of this debate arises from the different responses of the many species used, the diversity of approaches to manipulate cortisol levels, and the sampling techniques and duration. Given the extreme differences in experimental approach, it is not surprising that inconsistencies exist within the literature. This review attempts to delineate common themes on the physiological and metabolic roles of cortisol in teleost fishes and to suggest new approaches that might overcome some of the inconsistencies on the role of this multifaceted hormone. We detail the dynamics of cortisol, especially the exogenous and endogenous factors modulating production, clearance and tissue availability of the hormone. We focus on the mechanisms of action, the biochemical and physiological impact, and the interaction with other hormones so as to provide a conceptual framework for cortisol under resting and/or stressed states. Interpretation of interactions between cortisol and other glucoregulatory hormones is hampered by the absence of adequate hormone quantification, resulting in correlative rather than causal relationships.

Estimating the size-selection curves of towed gears, traps, nets and hooks

Abstract: A general statistical methodology for analysis of selectivity data from any type of fishing gear is presented. This formal statistical modelling of selectivity is built on explicit definitions of the selection process and specification of underlying assumptions and limitations, and this gives the resulting estimates of gear selectivity (and possibly fishing power) a clear interpretation. Application of the methodology to studies using subsampled catch data and to towed gears having windows or grids is outlined, and examples applied to passive nets and towed gears are presented. The analysis of data from replicate deployments is covered in detail, with particular regard to modelling the fixed and random effects of between-haul variation. Recent developments on the design of selectivity experiments are introduced and demonstrated.

Ichthyofaunal assemblages in estuaries: A South African case study

Abstract: This review places the life-history styles of fishes associated with South African estuaries in a global context and presents a classification system incorporating all the major life-history categories for estuary-associated fish species around the world. In addition, it documents the early life histories of the major fish groups in South African estuaries, with particular emphasis on the differing modes of estuarine utilization by marine, estuarine and freshwater taxa. This review details factors influencing the ichthyofaunal community structure in South African estuaries. The availability of fish for recruitment into an estuary depends primarily upon the distributional range of euryhaline marine and estuarine species, with tropical and temperate taxa showing marked abundance trends. Within a particular biogeographic region, however, estuarine type and prevailing salinity regime have a major influence on the detailed ichthyofaunal structure that develops. There is an increasing preponderance of marine fish taxa when moving from a freshwater-dominated towards a seawater-dominated type of system, and a decline in species diversity between subtropical estuaries in the north-east and cool temperate systems in the south-west. Similar declines in fish species diversity between tropical and temperate estuaries in other parts of the world are highlighted. Fish assemblages in estuaries adjust constantly in response to changing seasons, salinities, turbidities, etc. Despite persistent fluctuations in both the biotic and abiotic environment, the basic ichthyofaunal structure appears to have an underlying stability and to be predictable in terms of the response of individual species to specific conditions. This stability seems to be governed by factors such as the dominance of eurytopic taxa within estuarine assemblages and the robust nature of food webs within these systems. The predictability arises from factors such as the seasonality associated with estuarine spawning cycles and juvenile fish recruitment patterns. These patterns, together with a well-documented resilience to a wide range of physico-chemical and biotic perturbations, appear to be an underlying feature of fish assemblages in estuaries around the world. In contrast to marine fish species, estuary-associated taxa have received little conservation attention. Apart from the designation of protected areas, the main direct means of conserving estuary-associated fish stocks include habitat conservation and controls over fishing methods, effort, efficiency and seasonality. Of these, the conservation of fish habitats, the most important, because healthy aquatic environments invariably support healthy fish populations. The use of estuarine sanctuaries for fish conservation is briefly reviewed, as well as the legislation governing the USA National Estuarine Research Reserve System (NERRS) and the Australian Marine and Estuarine Protected Area (MEPA) system. It is concluded that South Africa requires an expansion of the existing Estuarine Protected Area (EPA) network, as well as the upgrading of selected 'estuarine reserves' where fishing is permitted, into 'estuarine sanctuaries' where no exploitation of biological resources is allowed.

Species pairs of north temperate freshwater fishes: Evolution, taxonomy, and conservation

Abstract: Many fish species contain morphologically, ecologically and geneticallydistinct populations that are sympatric during at least some portion oftheir life cycle. Such reproductively isolated populations act asdistinct biological species, but are identified by a common Latinbinomial. These ‘species pairs’ are particularly common in freshwaterfish families such as Salmonidae, Gasterosteidae and Osmeridae and aretypically associated with postglacial lakes in north temperateenvironments. The nature of the divergences between sympatric species,factors contributing to reproductive isolation, and modes of evolutionare reviewed with particular emphasis on benthic and limnetic pairs ofthreespine sticklebacks, Gasterosteus aculeatus, and anadromous(sockeye salmon) and nonanadromous (kokanee) pairs of Oncorhynchusnerka. Phylogenetic analyses typically indicate that divergencesbetween members of replicate pairs have occurred independently and,hence, particular phenotypes are not monophyletic. Consequently,taxonomic resolution of such ‘species complexes’ is a vexing problem foradherents to our traditional Linnaean classification system. Sympatricspecies pairs represent a significant component of the biodiversity oftemperate freshwater ecosystems which may be underestimated because oursystem of formal taxonomy tends to obscure diversity encompassed byspecies pairs. Conservation of such systems should be recognized as apriority without formal taxonomic designation of members of speciespairs because taxonomic resolution will likely continue to proveextremely difficult when employing traditional hierarchies andprocedures.

Fisheries management in the twenty-first century: will new paradigms apply?

Abstract: The last decade has seen growing concern at the uncertain effectiveness of most fisheries assessment and management approaches as reflected by trends in global landing statistics published by FAO. These imply full exploitation of the majority of fishery resources and a serious overcapitalization of fleets at the global level. Projected increases in demand, future prices for fisheries products, and impacts of growing world populations on the ecosystem all require an urgent search for improved management frameworks. Improved management of fisheries requires, first, an understanding of the axioms and working assumptions underlying the current approaches and how these evolved in response to regional or local conditions and target species. This should promote integration of methodologies which better reflect local situations and can be expressed in the form of one or more working paradigms. These paradigms should incorporate ecosystem considerations, including environmental fluctuations and socio-economic factors. They should not assume that current production levels are independent of natural fluctuations and human impacts and should recognize the dangers of maintaining open access to marine resources throughout their seasonal cycle, life history and distribution range. ‘Wide-use’ management paradigms incorporating explicit user rights, participatory management and inputs from a variety of disciplines and stakeholders are becoming popular, but must operate within a hierarchy of pre-negotiated responses to pre-specified limit reference points so that social and economic options are not lost because conservation issues have not been given precedence. Academic and research institutions could aid the management process by more participation, by promoting interdisciplinary teamwork with stakeholders and by breaking down excessive specialization and regionalization within fisheries studies. On the management side, the key elements for improving the situation seem to be consultative management frameworks that explicitly incorporate ‘watchdog’ functions and implement ‘precautionary’ approaches to management. Risk-averse strategies are appropriate but, given the high level of uncertainty that managers face with natural systems, ‘fail-safe’ management with redundancy, both in the data sources they rely on for fishery performance and in the management measures applied, seem appropriate. For near-shore resources, governments could consider partly devolving management responsibility to appropriate levels in society, involving coastal communities, individual use rights and other vehicles for allocating access. Changing emphasis of modern technology from fisheries exploitation to improved management will be one aspect of successful future management systems, perhaps incorporating geotemporally defined access rights to near-shore and shelf resources. Recent international agreements, including the formal ratification of the Law of the Sea, show that governments are prepared for more ecologically appropriate approaches. The key stake of the fisheries industry in sustainable fisheries development needs supporting, particularly for developing countries, now the major source of aquatic marine products. High priorities for management of marine resources are rebuilding depleted resources and restoring habitats, with concern for maintaining genetic and ecological diversity. There will be a need to consider impacts of global trade on conservation of resources for future generations, if proper management is to be maintained in the face of growing demand. International agreements of relevance to future management paradigms which are compatible with the Law of the Sea Convention (and each other), include Agenda 21 of UNCED, the Biodiversity Convention, the UN Agreement on Straddling Fish Stocks and Highly Migratory Fish Stocks, the Compliance Agreement and the FAO Code of Conduct for Responsible Fisheries. Such agreements, ratified or now open for signature, provide a comprehensive basis for future ‘customary law’ that can assist authorities in constructing appropriate management frameworks. Current concern remains with application of these agreements in international waters, where limited access as required for proper management still has not been established.

A framework for providing scientific advice for the management of new and developing invertebrate fisheries

Abstract: A framework is developed for the provision of scientific advice to support the management of new and developing marine invertebrate fisheries. These fisheries often occur on species for which little biological or exploitation information is available. The framework explicitly endorses the precautionary approach to fisheries management and research. Three general management strategies (size/sex limits, regulation by total allowable catch, control of the exploitation rate) and their needs for supporting scientific information are identified. The significance of spatial pattern, and of recognizing the need for different approaches to obtain scientific information and to manage sedentary benthic and mobile pelagic species, is a central theme. Three 'phases' are proposed to obtain the necessary scientific information: (a) Phase 0, 'collecting existing information', consisting of syntheses of available biological and fisheries information on the target (and similar) species, leading to formulation of potential management strategies; (b) Phase 1, 'collecting new information', to obtain the essential information that is lacking or insufficient from the Phase 0 analysis, and to evaluate alternative management strategies and propose regulatory actions; and (c) Phase 2, 'fishing for commerce', to implement the chosen management actions and to monitor fishing operations, so as to increase the information base available to refine the results from previous phases. Phase 1 activities may consist of surveys, site-specific depletion experiments and studies to obtain biological information, and development of experimental management areas to test different exploitation rates. A strategy that includes establishing reserve areas recognises the inherent uncertainties associated with developing fisheries and provides a buffer against mistakes or 'surprises'; it also provides control areas to compare stock productivity in fished and unfished locations. The application of this framework to a developing sea cucumber fishery in British Columbia is presented as an example. Throughout, strong interaction and collaboration among science, management, and stakeholders is crucial to the provision of scientific advice for precautionary management of new invertebrate fisheries.

Alloparental care in fishes

Abstract: Alloparental care, care directed at non-descendant young, presents a potential challenge to evolutionary ecologists because investment in non-descendant eggs and young gives the appearance of maladaptive behaviour. Yet wherever there is parental care in fishes, there is usually alloparental care. As such, alloparental care is an integral part of care in fishes. Alloparental care appears to have arisen independently many times in disparate taxa. The chief reason for this is the low cost of care, relative to homeotherms, both in terms of low post-zygotic investment to nourish young, and low risk of predation to the parent during brood defence. In some cases, alloparenting is misdirected parental care and maladaptive. A celebrated example of brood parasitism in fish is that of the catfish Synodontis multipunctatus, which parasitizes broods of mouthbrooding cichlids. Previously unpublished data on the reproductive biology of S. multipunctatus are reported here. However, in the majority of cases, particularly for the widespread phenomena of zygote dumping (nest associates) in the Cyprinidae and adoption of non-descendant free-swimming young in brood-guarding Cichlidae, alloparental care is a mutualistic relationship maintained by natural selection. This review describes broad patterns of known examples of alloparental care, the pathways to adoption, and highlights the ways in which alloparents derive fitness benefits. By caring for non-descendant young, an alloparent may benefit by one or more of the following phenomena: acquisition of mates, confusion effect, dilution effect, selfish herd effect, selfish shepherd effect, kin selection, and reciprocal altruism. Although the breadth and diversity of examples of alloparental care in fishes is growing, to date, these accounts have been largely descriptive. Future research should be directed at careful documentation of the fitness consequences for both donor and alloparent. These are the data that are needed to fully understand the evolutionary underpinnings of alloparental care, and by extension, parental care.

Linking recruitment to trophic factors: revisiting the Beverton-Holt recruitment model from a life history and multispecies perspective

Abstract: The Beverton--Holt recruitment model can be derived from arguments about evolution of life history traits related to foraging and predation risk, along with spatially localized and temporarily competitive relationships in the habitats where juvenile fish forage and face predation risk while foraging This derivation explicitly represents two key biotic factors, food supply (I) and predator abundance (R), which appear as a risk ratio (R/I) that facilitates modelling of changes in trophic circumstances and analysis of historical data The same general recruitment relationship is expected whether the juvenile life history is simple or involves a complex sequence of stanzas; in the complex case, the Beverton--Holt parameters represent weighted averages or integrals of risk ratios over the stanzas The relationship should also apply in settings where there is complex, mesoscale variation in habitat and predation risk, provided that animals sense this variation and move about so as to achieve similar survival at all mesoscale rearing sites The model predicts that changes in food and predation risk can be amplified violently in settings where juvenile survival rate is low, producing large changes in recruitment rates over time

What is a fish species

Abstract: The formal processes of alpha-taxonomy ensure that species have uniquenames and can be identified No similar process is mandatory forinfraspecific variation, so the species is a uniquely importantpractical term At present, there is little agreement of the definitionof a species In the last 30 years, numerous concepts have beenproposed The nature of fish species is reviewed Clonal inheritance ofnuclear genes occurs in several lineages Hybridization is frequent,often leading to introgression, which may lead to extinction of speciesSpecies may have hybrid origins There is good evidence for parallelspeciation in similar habitats There are clearly exceptions to thecladistic assumption of dichotomous branching during speciation Siblingspecies may exist with no discernible niche differentiation Basic assumptions are violated for the recognition, phylogenetic,ecological and some formulations of the evolutionary species conceptsThe most satisfactory definitions are two of the earliest proposed inthe light of evolutionary theory The Darwinian view is that species arerecognizable entities which are not qualitatively distinct fromvarieties A restatement of this concept in genetic terms provides ameans of dealing with all forms of species known in present-day fishesThis modified Darwinian concept is operated through the application offuzzy logic rather than rigid definition This involves a search fordiscontinuities between species, rather than an a priori definition ofhow boundaries are to be determined A subset of Darwinian species areMayrian or ‘biological species’, which are characterized by theirdemonstrable reproductive isolation from other species The status of apopulation as a Mayrian species is a testable hypothesis Moleculartechniques allow this hypothesis to be tested more easily thanpreviously, at least when dealing with sympatric populations

Early Life Stage Mortality Syndrome in Fishes of the Great Lakes and Baltic Sea (American Fisheries Society Symposium 21). Edited by Gordon McDonald, John D. Fitzsimons and Dale C. Honeyfield

Abstract: Early Life Stage Mortality Syndrome in Fishes of the Great Lakes and Baltic Sea(American Fisheries Society Symposium 21). Edited by Gordon McDonald, John D. Fitzsimons and Dale C. Honeyfield. American Fisheries Society, Bethesda, MD, 1998. ISBN 1-888569-08-5, ISBN 0892-2284, $46.00 US. Soft cover, acid-free paper, pp. x + 177, 50 tables, 68 figures (8 in colour). Proceedings of the Symposium ‘Early Mortality Syndrome: Reproductive Disruptions in Fish of the Great Lakes, New York Finger Lakes, and the Baltic Region’, held at Dearborn, Michigan, USA, 28 August 1996. Available from: AFS Publication Fulfillment, PO Box 1020, Sewickley, PA 15143, USA (fax +1 412 741 0609).

Species concepts and phylogenetics

Abstract: Concepts of species proposed within the phylogenetic paradigm arecritically reviewed. Most so called ‘phylogenetic species concepts’ relyheavily on factors immaterial to phylogenetic hypotheses. Thus, theyhave limited empirical content and offer weak bases on which to makedecisions about real problems related to species. Any workable notion ofspecies relies on an explicit character analysis, rather than onabstract properties of lineages, narrative predications and speculationson tokogenetic relationships. Species only exist conjecturally, as thesmallest meaningful units for phylogenetic analysis, as based oncharacter evidence. Such an idea considers species to be conjecturesbased on similarity, that are subsequently subject to testing by theresults of analysis. Species, thus, are units of phylogenetic analysisin the same way as hypotheses of homology are units of comparablesimilarities, i.e. conjectures to be tested by congruence. Althoughmonophyly need not be demonstrated for species-level taxa, hypotheses ofrelationships are the only basis to refute species limits and guidenecessary rearrangements. The factor that leads to recognition ofspecies is similarity in observed traits. The concept of life cycle isintroduced as an important element in the discussion of species, as anefficient way to convey subsidiary notions of sexual dimorphism,polymorphism, polytypy and clusters of diagnosable semaphoronts. Thenotion of exemplars is used to expand the concept ofspecies-as-individual-organisms into a more generally usable concept.Species are therefore proposed for a diagnosable sample of(observed or inferred) life cycles represented by exemplars all of whichare hypothesized to attach to the same node in a cladogram, and whichare not structured into other similarly diagnosable clusters. Thisdefinition is character-based, potentially testable by reference to abranching diagram, and dispenses with reference to ancestor-descendantrelationships or regression into population concepts. It provides aworkable basis on which to proceed with phylogenetic analysis and abasis for that analysis to refute or refine species limits. A protocolis offered for testing hypotheses of species boundaries in cladograms.

Fish species – how and why

Abstract: It is argued, with selected examples from freshwaterfish systematics, that species should be viewed as anexpression of self-perpetuated clustered variation innature, conforming to the phylogenetic speciesconcept. The importance of species lies in thefunctional and structural significance of theirdiagnostic characters. Species can be nested by theircharacters into a tree diagram (phylogeny) orhierarchical alignment structure (classification) ofcharacter distribution, which may be taken to reflectevolution, the unifying theory of organismaldiversification. The phylogenetic species concept,which emphasizes recognition of a pattern ofvariation, describes better than any other proposedconcept the units called species by systematists.Other concepts are based on processes and normally donot permit recognition of particular taxa. Specieshave unique histories, and speciation may proceed bydifferent mechanisms. Whereas it may be postulatedthat speciation entails an irreversible change in thegenetic structure of taxa, recognized by phenotypicexpression and apparently also maintained to a largeextent by selection for a particular phenotype,species recognition must remain independent ofassumptions about species history and spatialdistribution. Species are monophyletic taxa and thespecies category does not differ significantly inphylogenetic regard from other systematic categories.Species as such are not necessarily evolutionaryunits. It is recommended to apply species names withreference to the diagnostic characters of the speciesand to abandon the type specimen described by theInternational Code of Zoological Nomenclature as anomenclatural reference unit.

Biology and Ecology of Fishes in Southern African Estuaries (Ichthyological Monographs of the J.L.B. Smith Institute of Ichthyology, No. 2)

Abstract: some and too far removed from the fishers. Upon reading many documents on management, the impression is often given that the fisher is the last person to be considered. Instead the fisher should be the starting point of the process. He (mostly he) should be involved in the management process, should be consulted over data gathering and should be involved in deciding the goals of the fishery. In informal conversation, many fishers acknowledge that fishing is taking too much of the stock. This acknowledgement needs to be developed into a desire to do something to render their resource sustainable. Only in this way will management measures work. Review of Northeast Fishery Stock Assessments is a good lesson in what is wrong with current fisheries management. It shows how the management process has become too elaborate, has lost track of who the management is being done for, and has allowed the desire to reduce biological uncertainty to stimulate the growth of large bureaucratic organizations that cannot respond flexibly to changing conditions. The advent of co-management regimes that are tailored to the needs of a particular fishery is an indication that many are now seeing the faults in the sorts of management regime described in this book. Review of Northeast Fishery Stock Assessments is almost like an internal report dressed up as a book. The cover is elegantly designed with an evocative picture by Winslow Homer calledThe Fog Warning. Inside, the design is less imaginative, with rather coarse-grained maps and figures, and in the appendix, some sections that look as if they are photocopies of overhead slides. For these reasons, this book is something that a fishery professional will appreciate for the lessons it teaches but the less specialized reader might find the book unappealing.

Watershed Restoration: Principles and Practices. Edited by J. E. Williams, C. A. Wood and M. P. Dombeck

Abstract: The section on marine fishes, introduced by B. Howell, is far too brief. There is a veritable tidal wave of effort going into stocking and enhancement of marine fishes, but Howell’s chapter and indeed the others in this section barely scratch the surface. Section IV on genetics is a little stronger, with a more extensive introductory chapter by G.R. Carvalho and T.F. Cross, and several chapters with area-specific details. Finally, section V, on management concerns, has a chapter each on codes of practice, evaluation, and economics, and two chapters on specific case studies. This is a valuable compilation and I am sure it will be frequently used to find both principles and case examples in the history of fish stocking and introduction. However, this book has two major weaknesses. First is the unbalanced geographic coverage: of the 36 papers, 29 deal with experience in Europe, three concern African lakes, two are from the Americas and two from Asia. Yet many of the impacts of stocking and introduction are very different depending upon the geographic isolation of the target habitats and the history of the region with respect to previous introduction. The impact of introductions in North and South America, most of Africa, almost all of Asia, Australia, New Zealand and Hawaii are all lacking. The vast experience in North America with stocking of Pacific salmon is missing. Perhaps the volume should have been entitled Stocking and Introduction of Fish in Europe with a few Other Examples ! The second chief weakness is the lack of any concluding chapter. Someone should have read all of the chapters and come to some conclusions. Let me just add the one that I particularly wish had been present. When reviewing the history of fish stocking and introduction around the world, it is clear that there have frequently been catastrophic or at least seriously damaging results, and that rarely – if ever – has either stocking or introduction provided the anticipated benefits without large unanticipated negative consequences. Thus while the codes of practice and guidelines for evaluation of new projects are useful, these should be tempered by the strong expectation that proposed introduction and stocking will not only fail to achieve their objectives but also hold the strong possibility of disaster. Thus anyone evaluating a proposal for a stocking or introduction should begin with a very strong prior belief that it won’t work and will be deleterious. Ray Hilborn Seattle, Washington Watershed Restoration: Principles and Practices . Edited by J. E. Williams, C. A. Wood and M. P. Dombeck. American Fisheries Society, Bethesda, MD, 1997. ISBN 1-888569-04-2 (hard cover, $50.00 US), 1-888569-05-0 (p/b, $40.00 US). Acid-free paper, pp. xxi + 561, 30 tables, 109 figures (35 in colour). Extensive list of references; glossary, species list, index. Available from: AFS Publication Fulfillment, PO Box 1020, Sewickley, PA 15143, USA.

Molecular markers and the species concept: New techniques to resolve old disputes?

Abstract: Key words: fish, molecular marker, speciation, species conceptIntroductionAlthough all biologists recognize the value of parti-tioning biodiversity into recognizable units organizedintodifferenthierarchicallevels, therehasbeena long-standing, and at times unhelpful, controversy on thenature and significance of the species as the basic unitof biodiversity. Despite the exhaustive considerationof various species concepts over many decades, thereappears to be no abatement to the outpouringof strongsentiments, as evidenced by the articles herein. Suchforceful and dedicated considerations are perhaps notsurprising in light of the fundamental role that speciesplay in the biological world, though have they reallyhelped our understandingof biodiversity? Here, in thisbrief personalized viewpoint, we do not present yetmore critiques of species concepts or their variants,but rather make some comments on the underlyingforcesgeneratingsuch focus, and considerwhethertheapplication of molecular genetic markers is an aid or ahindrance.Species as biological entitiesThe extensive (and often repetitive) literature onthe species concept reveals several features of thecontinuing dispute on the species concept: (1) mostauthors believe that the species is the only biologi-cally meaningful taxonomic unit, and that it is adefinable entity; (2) most authors vigorously defendtheir favourite (or their own) definition of that unit,and discard others as completely wrong; and (3)almost 250 years of Linnaeus’ binomial classificationof species were apparently insufficient to define thespecies to a level acceptable to most scientists. Theseobservations may give rise to the suspicion that thecourse of the species concept dispute is a result of‘typological’ thinking, as expressed in the typolog-ical species concept, and itself a result of Platonicphilosophy stating that there is an ideal ‘universal’with material manifestations(see Turner,this volume).While the typological species concept is now gener-ally disregarded, the search for an definable, ideal‘universal’ of a species, despite ubiquitous imperfectmanifestations of that ideal in the natural world, maybe a legacy of typological thinking in biology. This isnot to say that we do not need the species as a taxo-nomic unit, but rather that the biological reality of aspecies may not always be amenable to rigid defini-tion. It may be more helpful for the understanding ofbiodiversity and our research efforts to recognize theimperfections of each species concept and to acceptexceptions as a fact of life rather than a conceptualnuisance.Clearly, the species is crucial to the classifica-tion of biodiversity, and abandoning it would meanto throw our current description of biodiversity intodisarray. Nevertheless, the belief that the unit ofbiodiversity as defined by taxonomists is in all casesa real biological entity may be questionable, and thusthe search for a universal definition of that entity maybe futile. Indeed, an uncritical adherence to a givenspecies conceptmay be counter-productiveby fuellingadditional confusion and unnecessary dispute, and byaffecting the way many empirical studies are carriedout. For example, typological conceptions seem toinfluence many phylogenetic publications on closely

The Fishery Potential and Productivity of the Pelagic Zone of Lake Malawi / Niassa. Edited by Andrew Menz

Abstract: It is highly likely that, because of the imperatives for improvements in fish farming, our understanding of fish biology has progressed more in the last two decades than during any similar period. Successful fish production is essentially about manipulation of the environment, and of the fishes’ response to this, in order to affordably maximize survival and growth; Biology of Farmed Fishwill be of interest to anyone concerned with the reproduction, growth, health or genetics of fish, and their responses to and interactions with the environment. Although the authors in this book are mainly UK-based, they are recognized international experts in their fields and their contributions are essentially global. Each of the 12 chapters presents a succinct account of the principles of its subject area – both in general terms and in relation to the particular requirements and implications for fish culture – and provides specific examples to illustrate the points made. The first four chapters describe the biology of fish production, from reproduction through development and rearing, commenting particularly on the physiological, nutritional and environmental aspects and the constraints and problems involved. The next three chapters deal with threats to successful cultivation: parasites, the response of the immune system to diseases and stressors, and the effects of stress on all the foregoing. Readers are referred elsewhere for detailed information on fish diseases. Two chapters then cover the behavioural and physiological interactions between fish and culture conditions, in terms of both the requirements for successful rearing and the environmental impact of aquaculture itself. Chapters 10 and 11 describe the role that selection and genetic manipulation can play in promoting aquaculture and modifying its impact on the environment, and the potential application of molecular markers to evaluating and improving performance. Although much information presented in this book is relevant to all teleosts (there is not a single mention of any elasmobranch species), the greatest part of the research referred to has been carried out in temperate waters. As a balance, and possibly to provide a contrast between the cultural and economic imperatives driving aquaculture in NW Europe and North America and the simple necessity to produce food in much of the rest of the world, the final chapter concerns itself with the culture of warm-water species. From a list of over 100 species of fish recorded by FAO as having a production of more than 100 tonnes in 1995, some 40 might be regarded as requiring warm water. The book is extremely well presented, and repetition is minimized and comprehension aided by cross referencing between chapters. It does, however, assume a relatively advanced knowledge of each subject area and a good grasp of the English language, and I concur with the editors that the target audience is researchers, postgraduate students and professionals working on any aspect of fish biology or aquaculture (although not the rearing systems). There are relatively few figures and illustrations, which complement and enhance the text, and a number of tables which summarize information on the topics discussed. Each chapter has a substantial list of references, the vast majority of which are to be found in publications which should be readily available. In conclusion,Biology of Farmed Fishlives up to its claim to be a landmark volume presenting a generic account of the biology underlying fish culture, and it certainly provides a convenient point of access to the primary literature and earlier reviews.

The good, the bad, and the ugly: A critical look at species and their institutions from a user's perspective

Abstract: Over the past eight years my colleagues and I have been involved in a major project to make key information on fishes available to users, especially in developing countries (Froese and Pauly, 1998; http://www. fishbase.org/). There are about 25 000 species of fishes in the world of which over 7 000 are used by humans as food, for sport or as pets. Dealing with such large numbers meant that we depended heavily on taxonomic works to ensure that we assigned relevant information to the correct species. Eight years through the project we have covered 22 000 species, 40 000 synonyms, 80 000 common names, and 14 000 references. We have worked with over 300 collaborators, among them many taxonomists, and we have visited many museums. In this contribution I present our experiences in the catchy categories of ‘good’, ‘bad’, and ‘ugly’, not to offend anyone, but to provoke reactions that hopefully will lead to some of the changes that we as users of taxonomic information would like to see.

Fish haemoglobins: the order Clupeiformes

Abstract: The haemoglobin systems of the order Clupeiformes have been studied by several researchers in 41 species belonging to three out of its five families. Most of them were investigated in the native form using electrophoretic methods, and a few were also examined from the functional point of view. Both approaches corroborate the widespread view that acidic and basic haemoglobin components, which are structurally and functionally distinct, may be present in teleost fish. However, the former are always present, whereas the latter are often lacking, depending on the taxonomic group. Both kinds of components are found in families Clupeidae and Pristigasteridae, but only acidic ones in Engraulidae.

Review of Northeast Fishery Stock Assessments

Abstract: It is impossible in the available space to describe the individual papers, but one cannot ignore that of Parrish, who, in his essay on life history strategies for marine fishes in the late Holocene, points out the advantages of being small, bony, ugly and unpalatable to primates, and foresees the eventual ocean dominated by myctophids. In an impressive test of the Bakun paradigm, Faure and Cury examine eleven upwelling areas of the world, with three fish catch productivity indices, and five environmental parameters, to demonstrate the combination of environmental factors required for high fish productivity. This book marks a significant advance in the science of fishery oceanography and belongs in the library of everyone devoted to this increasingly productive field of marine science.

Stocking and Introduction of Fish. Edited by I. G. Cowx

Abstract: Zusammenarbeit (GTZ), GmbH, Eschborn, Federal Repulic of Germany; and International Center for Living Aquatic Resources Management (ICLARM), Manila, Philippines, pp. 189–206. Pauly D., Palomares M.L. and Gayanilo F.C. (1987) VPA estimates of monthly population length composition, recruitment, mortality, biomass and related statistics of Peruvian anchoveta, 1953 to 1981. In: Pauly D. and Tsukayama I. eds. The Peruvian Anchoveta and its Upwelling Ecosystem: Three Decades of Change(ICLARM Studies and Reviews, 15). Instituto del Mar del Perú (IMARPE), Callao, Peru; Deutsche Gesellschaft für Technische Zusammenarbeit (GTZ), GmbH, Eschborn, Federal Repulic of Germany; and International Center for Living Aquatic Resources Management (ICLARM), Manila, Philippines, pp. 142–166.

Global versus Local Changes in Upwelling Systems (Collection Colloques et séminaires)

Abstract: I set out to review this book with considerable anticipation. The subject is one I have thought about for many years, and I am acquainted with most of the editors and many of the authors. It soon became apparent that this treatise is of such interest and importance that one would need months of reading and pages of commentary to do it justice. The book resulted from the Climate and Eastern Ocean Systems Project (CEOS) of ORSTOM, NMFS, and ICLARM∗ which was devoted to the study of the potential effects of global and local environmental changes on the resources of upwelling systems, particularly those off Peru, Chile, California, Northwest, and Southwest Africa. These systems contain large stocks of sardines, anchovies and other small pelagic fishes and are dominated by processes of enrichment, concentration and retention that are functions of atmospheric forcing, ocean dynamics, and fresh water inflow, all sensitive to climate change. Through comparisons of forcing and response in these several systems, it was hoped that new generalizations would emerge. The papers are particularly refreshing since they feed one of my favorite prejudices: they recognize that not all major changes in fish stocks are caused by overfishing. Instead they focus on a search for envir-

Fishes of Antarctica: A Biological Overciew

Abstract: only now being properly documented and analysed. For example, more than 100 intrusive species are so far recorded from West Africa in 75 genera, 30 families and 14 orders; and in the Cross river alone, there are 33 from 166 species (20%) with a familial representation of 38%, or 16 from 42 families (Reid, 1996). Dr Whitfield (pp. 170, 220) collates even more impressive totals for southern Africa, with 155 estuary-associated fish species in 53 families, and notes in the preface that there are over 10 000 coastal marine species in the region (with 12% endemicity) which may represent about 15% of the world total for this general ecosystem. The author tackles the complexities of the estuarine ichthyology and biology in a systematic and logical way. He begins with the estuarine environment, ichthyological history and characteristics of the fishes, then follows through on species profiles and ecosystems and finally covers human impacts on estuaries and the crucial issue of conservation. There are 100 high-quality fish illustrations to support the text and most of these relate to the species profiles, which are also good. However, the three broad species groups recognized – marine, estuarine and freshwater – depend on an uncomfortable mix of evidence or assumptions of phylogeny and (a sometimes transzonal) reproductive biology. For example, how far is the inclusion ofAmbassis gymnocephalus in the estuarine group justified on current knowledge of phylogeny and reproduction? There are also associated biogeographical aspects (pp. 169–170) which would have merited a fuller interpretation in relation to phylogenetic rather than essentially ecological hypotheses. I particularly appreciated the concluding section on conservation. TheSouth African Red Data Book (Skelton, 1987) lists eight threatened endemic estuarine fish species from an estimated total of 38 (or 25% of all estuary-associated fishes). Among these, a pipefish ( Syngnathus watermeyeri ) s now critically endangered, as increasingly are other pipefishes and seahorses worldwide, sometimes from human impacts on their environment. Encouragingly, there is (Whitfield, p. 182) a strategic goal to implement a nationwide policy in South Africa to conserve estuaries and lagoons, no matter how large or small. Alan Whitfield’s broad evaluation will, I believe, be recognized as an essential step towards this goal, and his excellent research findings certainly represent a major contribution to our fundamental knowledge of estuaries. Reference