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Humanity's relationship with fish dates back to prehistory, when ancestral hominins evolved the capacity to exploit aquatic resources. The impacts of early fishing on aquatic ecosystems were likely minimal, as primitive technology was used to harvest fish primarily for food. As fishing technology became more sophisticated and human populations dispersed and expanded, local economies transitioned from hunter-gatherer subsistence to barter and complex trade. This set up a positive feedback ratcheting fishing technology, mercantilization, and the commoditization of fish. A historical narrative based on archaeology and documentary evidence follows the principal changes in fisheries through evolutionary, ancient, classical and medieval eras to modern times. Some local depletions are recorded from early fishing, but from the 1950s, massive impacts of serial depletions by size, species, area and depth are driven by commoditized fishery products. North Sea herring fisheries are described in detail. Today's severely depleted wild fish populations reflect social institutions built on global markets that value fish predominantly as a consumptive commodity, risking future ecological integrity and human food security. To sustain global fisheries, decommoditization strategies that sustain human and ecosystem relationships with fish beyond their commodity value are needed. [ABSTRACT FROM AUTHOR]

Many have documented the litany of disaster and depletion suffered by living organisms in the world’s oceans, where today anthropogenic impacts from fisheries and pollution on biodiversity and resilience are further exacerbated by threats of climate change. At the same time, the demand for sustainable seafood has never been greater. By presenting three challenges to marine biology, this article explores how we may be able to throw light upon practical measures that can mitigate, redress and avert some of the worst future scenarios whilst continuing to supply, and even increase, economic, social and nutritional benefits from seafood. First, I present a rigorous, multi-disciplinary, semi-quantitative ecosystem evaluation framework (EEF) that characterises the essential ecological features of different marine ecosystems and can evaluate the status of threats. The general framework is designed to work in the face of ignorance and quantifies uncertainty. An example is presented from recent work on seamounts. Second, a desperate need for food supplies will almost inevitably lead to further fishing down the trophic levels in marine food webs. Some have argued to do this deliberately to mitigate global problems of hunger, especially in the face of concerns about the sustainability of terrestrial agriculture, and we can be sure that economic pressures and market values for increasingly scarce protein will lead to tendencies of this type. One example is a possible increased exploitation of krill, which at first sight presents vastly increased amounts of protein that could be harvested. Here, I show how large but potentially sustainable levels of catch may be estimated in a precautionary fashion. Third, inter alia, a practical restoration agenda is discussed. The importance of historical reconstruction is exemplified by ‘Back to the Future’ research which attempts to use quantitative descriptions of past ecosystems to emplace practical restoration goals for management (such as Optimal Restorable Biomass, ORB), while quantifying risks in the management of marine ecosystems from climate and uncertainty. All three areas and their examples represent work-in-progress, and their credibility and utility pivot on the quality of our insight into critical ecological processes and on the widespread adoption of rational, precautionary policies. Moreover, they present profound scientific and human challenges to the science of marine biology. [ABSTRACT FROM AUTHOR]

A primary challenge of animal surveys is to understand how to reliably sample populations exhibiting strong spatial heterogeneity. Building upon recent findings from survey, tracking and tagging data, we investigate spatial sampling of a seasonally resident population of Atlantic bluefin tuna in the Gulf of Maine, Northwestern Atlantic Ocean. We incorporate empirical estimates to parameterize a stochastic population model and simulate measurement designs to examine survey efficiency and precision under variation in tuna behaviour. We compare results for random, systematic, stratified, adaptive and spotter-search survey designs, with spotter-search comprising irregular transects that target surfacing schools and known aggregation locations (i.e., areas of expected high population density) based on a priori knowledge. Results obtained show how survey precision is expected to vary on average with sampling effort, in agreement with general sampling theory and provide uncertainty ranges based on simulated variance in tuna behaviour. Simulation results indicate that spotter-search provides the highest level of precision, however, measurable bias in observer-school encounter rate contributes substantial uncertainty. Considering survey bias, precision, efficiency and anticipated operational costs, we propose that an adaptive-stratified sampling alone or a combination of adaptive-stratification and spotter-search (a mixed-layer design whereby a priori information on the location and size of school aggregations is provided by sequential spotter-search sampling) may provide the best approach for reducing uncertainty in seasonal abundance estimates. [ABSTRACT FROM AUTHOR]

Direct assessment of the abundance of highly migratory pelagic species, such as tuna, is rarely available and most indices are based on catch information. We estimate the seasonal abundance of North Atlantic bluefin tuna, Thunnus thynnus, in the Gulf of Maine (GOM) from a 3-year aerial survey conducted with commercial spotter pilots, while also utilizing findings from analyses of tracking and tagging data. We apply statistical correction and calibration to seasonal abundance estimates accounting for measured changes in horizontal and vertical movement behaviour, size, shape and aggregation of bluefin tuna schools. Our approach relies on ecological knowledge of bluefin tuna to extrapolate survey observations across areas not sampled by correcting survey abundance estimates based on range of movement search pattern and depth preference. We demonstrate how separate findings obtained through the analysis of data collected across different spatial and temporal scales can be integrated to correct and calibrate estimates of population abundance. We obtain fitted estimates of seasonal abundance of bluefin tuna in the GOM during 1994–1996 in the range of 45,000–51,000 individuals. If tuna behaviour is not accounted for, we estimate that the base or residual survey precision would be 4–7% determined from analysis of recent spotter survey data in the study region. We estimate the precision in estimating seasonal abundance accounting for tuna behaviour to lie within a range of 1,301–3,302%. Under hypothetical future improvements in survey design that achieve a precision of 20% in transect length and placement, we calculate net-precision to lie within a range of 82–93%. This calculation assumes reducible uncertainty in school size estimation and irreducible uncertainty in movement and school-aggregation behaviour. We infer that survey precision could be further reduced by 43–32% to attain 10–50% in which a 3–8 years adaptive survey design may reliably detect a seasonal abundance trend. [ABSTRACT FROM AUTHOR]

Assesses the need for sustainable fisheries around the world. History of fishing and fisheries; Impact of fisheries on ecosystem and biodiversity; Reasons for the overcapitalization of the world's fisheries; Biological constraints to fisheries and aquaculture. INSETS: Single-species stock assessments;Trophic levels as indicators of fisheries impacts;Sustainable coral reef fisheries: an oxymoron?.

The cover of the 1993 reprint of Beverton and Holt's book bears a diagram, its significance previously unrecognized, that expresses extinction due to fishing. This paper traces the concept to self-regenerating yield models in their 1957 book, its numerical development therein far in advance of its reinvention 30 years later. Local extinction constitutes a critical impact of fisheries on aquatic ecosystems that has been too often downplayed by fisheries science. [ABSTRACT FROM AUTHOR]

1. Methods for producing and analyzing long-term three-dimensional records of the positions of individuals within fish schools are described. Detailed analysis of internal structure and overall shapes of schools of three species which school to varying degrees are reported: Data from cod (Gadus morhua), a weak facultative schooler, saithe (Pollachius virens), a strong facultative schooler, and herring (Clupea harengus), an obligate schooler, are presented. 2. Fish do not position themselves at random within schools (Figs. 1 and 2). This is shown to result from the maintenance of minimum approach distances between fish (Fig. 3). Comparison of the frequency of neighbors at different distances with that expected at random (Fig. 3), however, demonstrates that fish space themselves more regularly than one would expect if the structure resulted wholly from minimum approach distances. 3. Herring and saithe are shown to swim at nearly but not exactly the same depth as their neighbors (Fig. 5). Neighbors are more-or-less equally common in all directions (bearings) around fish, although herring show some tendency toward taking up positions at 45° and 135° the positions expected if school structure were a cubic lattice. School structure is present in a statistical sense only. 4. Herring are shown to maintain proportionately larger interfish distances than do saithe or cod (Fig. 7). These results are discussed in terms of the body structure of the three species and the antipredator function of schooling. Shape of cod schools and, to a lesser degree, saithe schools, is shown to be highly variable. Herring schools, however, appear fairly constant in their external shape (Fig. 10). 5. Factors affecting the structure of schools of saithe are studied. Increasing the number of fish in the school or the speed at which it is swimming results in smaller interfish distances (Figs. 8 and 9). [ABSTRACT FROM AUTHOR]

Quantitative analyses of the effects of temporary blindfolding (BL) or lateralis section (LS) on the schooling performance of saithe ( Pollachius virens) are reported. Comparison of effects of the sensory deprivations on school structure and dynamics allow determination of the relative roles of the lateral lines and vision in normal schooling. Extended 3-dimensional records were made of the positions of sensorily deprived individuals in normal schools as well as whole schools with sensory treatments. We conclude that the role of the lateral line in schooling is much greater than has been recognised previously. Our experiments suggest that characteristic NND in a travelling school is maintained by opposing forces of attraction and repulsion mediated by stimuli perceived by the visual and lateralis systems respectively. School structure and dynamics depend upon both senses, with vision primarily important for the maintenance of position and angle between fish and the lateral lines primarily important for monitoring the swimming speed and direction of travel of neighbors. [ABSTRACT FROM AUTHOR]

The authors urge that countries need to fully adopt the voluntary Code of Conduct for Responsible Fisheries, which was developed by the Food and Agriculture Organization of the United Nations. This recommendation derives from the ways in which overfishing has significantly reduced fish populations in the world's oceans.