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Eco-Label Conveys Reliable Information on Fish Stock Health to Seafood Consumers

Citation Information: Gutiérrez NL, Valencia SR, Branch TA, Agnew DJ, Baum JK, et al. (2012) Eco-Label Conveys Reliable Information on Fish Stock Health to Seafood Consumers. PLoS ONE 7(8): e43765. doi:10.1371/journal.pone.0043765

Abstract: Concerns over fishing impacts on marine populations and ecosystems have intensified the need to improve ocean management. One increasingly popular market-based instrument for ecological stewardship is the use of certification and eco-labeling programs to highlight sustainable fisheries with low environmental impacts. The Marine Stewardship Council (MSC) is the most prominent of these programs. Despite widespread discussions about the rigor of the MSC standards, no comprehensive analysis of the performance of MSC-certified fish stocks has yet been conducted. We compared status and abundance trends of 45 certified stocks with those of 179 uncertified stocks, finding that 74% of certified fisheries were above biomass levels that would produce maximum sustainable yield, compared with only 44% of uncertified fisheries. On average, the biomass of certified stocks increased by 46% over the past 10 years, whereas uncertified fisheries increased by just 9%. As part of the MSC process, fisheries initially go through a confidential pre-assessment process. When certified fisheries are compared with those that decline to pursue full certification after pre-assessment, certified stocks had much lower mean exploitation rates (67% of the rate producing maximum sustainable yield vs. 92% for those declining to pursue certification), allowing for more sustainable harvesting and in many cases biomass rebuilding. From a consumer’s point of view this means that MSC-certified seafood is 3–5 times less likely to be subject to harmful fishing than uncertified seafood. Thus, MSC-certification accurately identifies healthy fish stocks and conveys reliable information on stock status to seafood consumers.

Multivariate Statistical Analysis of Distribution of Deep-Water Gorgonian Corals in Relation to Seabed Topography on the Norwegian Margin

Citation Information: Tong R, Purser A, Unnithan V, Guinan J (2012) Multivariate Statistical Analysis of Distribution of Deep-Water Gorgonian Corals in Relation to Seabed Topography on the Norwegian Margin. PLoS ONE 7(8): e43534. doi:10.1371/journal.pone.0043534

Abstract: Investigating the relationship between deep-water coral distribution and seabed topography is important for understanding the terrain habitat selection of these species and for the development of predictive habitat models. In this study, the distribution of the deep-water gorgonians, Paragorgia arborea and Primnoa resedaeformis, in relation to terrain variables at multiple scales of 30 m, 90 m and 170 m were investigated at Røst Reef, Traena Reef and Sotbakken Reef on the Norwegian margin, with Ecological Niche Factor Analysis applied. To date, there have been few published studies investigating this aspect of gorgonian distribution. A similar correlation between the distribution of P. arborea and P. resedaeformis and each particular terrain variable was found at each study site, but the strength of the correlation between each variable and distribution differed by reef. The terrain variables of bathymetric position index (BPI) and curvature at analysis scales of 90 m or 170 m were most strongly linked to the distribution of both species at the three geographically distinct study sites. Both gorgonian species tended to inhabit local topographic highs across all three sites, particularly at Sotbakken Reef and Traena Reef, with both species observed almost exclusively on such topographic highs. The tendency for observed P. arborea to inhabit ridge crests at Røst Reef was much greater than was indicated for P. resedaeformis. This investigation identifies the terrain variables which most closely correlate with distribution of these two gorgonian species, and analyzes their terrain habitat selection; further development of predictive habitat models may be considered essential for effective management of these species.

Using Age-Based Life History Data to Investigate the Life Cycle and Vulnerability of Octopus cyanea

Citation Information: Herwig JN, Depczynski M, Roberts JD, Semmens JM, Gagliano M, et al. (2012) Using Age-Based Life History Data to Investigate the Life Cycle and Vulnerability of Octopus cyanea. PLoS ONE 7(8): e43679. doi:10.1371/journal.pone.0043679

Abstract: Octopus cyanea is taken as an unregulated, recreationally fished species from the intertidal reefs of Ningaloo, Western Australia. Yet despite its exploitation and importance in many artisanal fisheries throughout the world, little is known about its life history, ecology and vulnerability. We used stylet increment analysis to age a wild O. cyanea population for the first time and gonad histology to examine their reproductive characteristics. O. cyanea conforms to many cephalopod life history generalisations having rapid, non-asymptotic growth, a short life-span and high levels of mortality. Males were found to mature at much younger ages and sizes than females with reproductive activity concentrated in the spring and summer months. The female dominated sex-ratios in association with female brooding behaviours also suggest that larger conspicuous females may be more prone to capture and suggests that this intertidal octopus population has the potential to be negatively impacted in an unregulated fishery. Size at age and maturity comparisons between our temperate bordering population and lower latitude Tanzanian and Hawaiian populations indicated stark differences in growth rates that correlate with water temperatures. The variability in life history traits between global populations suggests that management of O. cyanea populations should be tailored to each unique set of life history characteristics and that stylet increment analysis may provide the integrity needed to accurately assess this.

Spatio-temporal distribution and seasonal population dynamics of the jellyfish Aurelia aurita s.l. studied with Dual-frequency IDentification SONar (DIDSON)

Citation Information: J. Plankton Res. (2012) doi: 10.1093/plankt/fbs057 First published online: August 27, 2012

Authors: Ryosuke Makabe, Takuya Kurihara and Shin-Ichi Uye

Abstract: Deployment of a Dual-frequency IDentification SONar (DIDSON) revealed the seasonal variations in spatial distribution and abundance of medusae of the common jellyfish, Aurelia aurita s.l. (detectable bell diameters: ca. ≥5 cm) in a shallow (max. depth: ∼6 m) Japanese brackish-water lake in between October 2008 and October 2009. The medusae were usually in patchy aggregations, more prominently so during warm seasons. Integration of the DIDSON-detected medusae with smaller ones estimated from the bell diameter composition in net hauls enabled us to study their seasonal population dynamics. Abundance was highest in June, due to recruitment, and declined to a relatively stable level in August and thereafter. The population carbon biomass was highest in October due to somatic growth of individual medusae. The annual mean biomass (63.8 mg C m−3) was much higher than that of mesozooplankton (26.0 mg C m−3), suggesting a substantial top-down impact. The DIDSON is an effective tool for studies of the spatial distribution and population dynamics of large jellyfish species like A. aurita. Concomitant net sampling to determine the bell diameter composition is required to offset the geometric limitations of this instrument.

Potential trophodynamic and environmental drivers of steelhead (Oncorhynchus mykiss) productivity in the North Pacific Ocean

Citation Information: ATCHESON, M. E., MYERS, K. W., DAVIS, N. D. and MANTUA, N. J. (2012), Potential trophodynamic and environmental drivers of steelhead (Oncorhynchus mykiss) productivity in the North Pacific Ocean. Fisheries Oceanography, 21: 321–335. doi: 10.1111/j.1365-2419.2012.00627.x

Abstract: Information on prey availability, diets, and trophic levels of fish predators and their prey provides a link between physical and biological changes in the ecosystem and subsequent productivity (growth and survival) of fish populations. In this study two long-term data sets on summer diets of steelhead (Oncorhynchus mykiss) in international waters of the central North Pacific Ocean (CNP; 1991–2009) and Gulf of Alaska (GOA; 1993–2002) were evaluated to identify potential drivers of steelhead productivity in the North Pacific. Stable isotopes of steelhead muscle tissue were assessed to corroborate the results of stomach content analysis. We found the composition of steelhead diets varied by ocean age group, region, and year. In both the GOA and CNP, gonatid squid (Berryteuthis anonychus) were the most influential component of steelhead diets, leading to higher prey energy densities and stomach fullness. Stomach contents during an exceptionally warm year in the GOA and CNP (1997) were characterized by high diversity of prey with low energy density, few squid, and a large amount of potentially toxic debris (e.g., plastic). Indicators of good diets (high proportions of squid and high prey energy density) were negatively correlated with abundance of wild populations of eastern Kamchatka pink salmon (O. gorbuscha) in the CNP. In conclusion, interannual variations in climate, abundance of squid, and density-dependent interactions with highly-abundant stocks of pink salmon were identified as potential key drivers of steelhead productivity in these ecosystems. Additional research in genetic stock identification is needed to link these potential drivers of productivity to individual populations.

Hybrid morphological modelling of shoreline response to a detached breakwater

Citation Information: Coastal Engineering; Volume 71, January 2013, Pages 13–27

Authors: Sten Esbjørn Kristensen, Nils Drønen, Rolf Deigaard, Jørgen Fredsoe

Abstract: We present a new type of model for calculating morphological changes induced by the presence of breakwaters. The model combines a process based area model, used to calculate the sediment transport field in the two horizontal dimensions, with a simplified morphological updating scheme where the evolving cross-shore profile is described by a limited number of parameters. The hybrid morphological model is a strong tool for medium and long term modelling because it is cost effective while containing important features of the sediment transport description.

Two versions of the model are developed in order to study the evolution of beach morphology: one suited for offshore breakwaters (1D model) and one mainly dedicated to coastal breakwaters (“1.5D” model).

The version for offshore breakwaters is first presented and tested against field observations of salient evolution. The model is then applied to a model study of the principle correlations between evolving salients (spatial and temporal scales), the characteristic dimensions of the breakwater (distance to shore and alongshore length) and wave climate (wave height, normal and oblique wave incidence).

The second version is applied to investigate in more detail the evolving morphology behind coastal breakwaters. It is demonstrated how the model is able to calculate the evolution of either salient or tombolo planforms, and furthermore it is shown that the results are in reasonable agreement with existing rules.

Spawning location of Norway pout (Trisopterus esmarkii Nilsson) in the North Sea

Citation Information: Nash, R. D. M., Wright, P. J., Matejusova, I., Dimitrov, S. P., O'Sullivan, M., Augley, J., and Höffle, H. 2012. Spawning location of Norway pout (Trisopterus esmarkii Nilsson) in the North Sea. – ICES Journal of Marine Science, 69:8.

Abstract: The northern region of the North Sea (56–62°N) was sampled in February/March 2009 for eggs and in May 2010 for larvae. To aid in the identification of Norway pout stage I eggs and distinguish them from other ‘cod-like’ eggs, a Taq-Man probe was designed for this species and used here. Stage I Norway pout egg diameters collected from the field were in the range 1.03–1.28 mm and largely overlapped with the size range determined for whiting (Merlangius merlangus). The distribution of Norway pout stage I eggs in 2009 revealed the distribution of spawning in the North Sea and showed that it was similar to the distribution of 2 + Norway pout taken during the International Bottom Trawl Surveys (IBTS) over the same period covering the whole North Sea. The larvae sampled in 2010 were largely in the same area; however, larger larvae occurred to the south-east of the survey area, suggesting advection of young stages from the principal spawning areas in the north-western North Sea to the south-east and toward the Skagerrak.

Otolith microstructure analysis to resolve seasonal patterns of hatching and settlement in western Baltic cod

Citation Information: Rehberg-Haas, S., Hammer, C., Hillgruber, N., Hüssy, K., and Temming, A. 2012. Otolith microstructure analysis to resolve seasonal patterns of hatching and settlement in western Baltic cod. – ICES Journal of Marine Science, 69:8.

Abstract: Previous studies showed that Baltic cod (Gadus morhua) settle to demersal life at a given size, while the annulus is formed seasonally, irrespective of size. The goal of this study was to examine the timing of check formation in juvenile Baltic cod otoliths to validate macrostructural ageing and to differentiate between true annuli and secondary structures such as settlement checks. Otoliths were collected from fish off Fehmarn Island in 2008 and 2009, and were examined for macrostructural and microstructural patterns using light and scanning electron microscopy. All fish examined were age-0. Back-calculation of hatch dates indicated hatching from April to June and from February to August in 2008 and 2009, respectively. Juveniles formed either one or two translucent rings. The first translucent ring started to form ∼3 months post-hatch and was interpreted as a settlement check, since it appeared to be a function of age and/or size and not season. Deposition of the second ring began in mid October to early November irrespective of fish size and/or age, thus indicating that this ring may represent the first annulus of Baltic cod. Both rings were clearly distinguishable in individuals hatched between February and May, but were merged in those fish where settlement coincided with the seasonally formed second ring.

Efficacy of conservation measures for the American lobster: reproductive value as a criterion

Citation Information: Xu, C., and Schneider, D. C. 2012. Efficacy of conservation measures for the American lobster: reproductive value as a criterion – ICES Journal of Marine Science, 69: 1831–1839.

Abstract: Reproductive value takes into account both current and future value, effectively characterizing the value of an individual to the population. In this study, we use reproductive value as a criterion to evaluate the effectiveness of several conservation measures that have been undertaken or proposed for the American lobster (Homarus americanus) fishery in Newfoundland. These measures are slot fishing (i.e. no fishing below or above certain sizes), marine protected areas (MPAs), V-notching, and window fishing (i.e. no fishing within a size window). Reproductive value was estimated by using catch length data available from commercial fisheries and research surveys. We found that MPAs had the greatest effect, followed by V-notching and slot-fishing. MPAs resulted in an average increase of 64.9% in total reproductive value, V-notching an average increase of 18.3%, and slot fishing an average increase of 16.8%. In general, window fishing was not effective unless the size of the window was large. For instance, an average increase of 8.7% in total reproductive value would require a wide window (100–129 mm). Our results provide a scientific basis for evaluating conservation measures in a way that integrates population demographical information with information from commercial fisheries and research surveys.

The response of herring to high crowding densities in purse-seines: survival and stress reaction

Citation Information: Tenningen, M., Vold, A., and Olsen, R. E. 2012. The response of herring to high crowding densities in purse-seines: survival and stress reaction. – ICES Journal of Marine Science, 69:8.

Abstract: To study the effects of crowding in purse-seines on the survival and stress response of herring (Clupea harengus), large-scale field experiments were conducted in the North Sea during 2008 and 2009. The mortality was 28% at a crowding density of 221 kg m−3 and increased further with increasing density. Crowding densities <150 kg m−3 did not result in any additional mortality compared with the control group (0.9–2.0%). Smaller herring and herring with a lower condition factor were more vulnerable to the effects of crowding. Blood analyses showed a significant increase in cortisol, lactate, and blood ions in the crowded fish. Lactate returned to control levels 2 d post-stress, whereas cortisol and blood ion levels continued to increase during the 4- to 5-d monitoring period. Furthermore, plasma glucose appeared to be substantially reduced at the end of the trial, indicating that the herring were incapable of restoring homeostasis and were approaching energy exhaustion. These results provide important information about the crowding densities that can be tolerated in the purse-seine fisheries for herring and will benefit future development of guidelines for purse-seine slipping operations.

Contrasting trends in sea ice and primary production in the Bering Sea and Arctic Ocean

Citation Information: Brown, Z. W., and Arrigo, K. R. 2012. Contrasting trends in sea ice and primary production in the Bering Sea and Arctic Ocean. – ICES Journal of Marine Science, 69:7.

Abstract: Satellite remote sensing data were used to examine recent trends in sea-ice cover and net primary productivity (NPP) in the Bering Sea and Arctic Ocean. In nearly all regions, diminished sea-ice cover significantly enhanced annual NPP, indicating that light-limitation predominates across the seasonally ice-covered waters of the northern hemisphere. However, long-term trends have not been uniform spatially. The seasonal ice pack of the Bering Sea has remained consistent over time, partially because of winter winds that have continued to carry frigid Arctic air southwards over the past six decades. Hence, apart from the “Arctic-like” Chirikov Basin (where sea-ice loss has driven a 30% increase in NPP), no secular trends are evident in Bering Sea NPP, which averaged 288 ± 26 Tg C year−1 over the satellite ocean colour record (1998–2009). Conversely, sea-ice cover in the Arctic Ocean has plummeted, extending the open-water growing season by 45 d in just 12 years, and promoting a 20% increase in NPP (range 441–585 Tg C year−1). Future sea-ice loss will likely stimulate additional NPP over the productive Bering Sea shelves, potentially reducing nutrient flux to the downstream western Arctic Ocean.

Spring partitioning of Disko Bay, West Greenland, by Arctic and Subarctic baleen whales

Citation Information: Laidre, K. L., and Heide-Jørgensen, M. P. 2012. Spring partitioning of Disko Bay, West Greenland, by Arctic and Subarctic baleen whales. – ICES Journal of Marine Science, 69:7.

Abstract: Movements of co-occurring bowhead (Balaena mysticetus) and humpback (Megaptera novaeangliae) whales in Disko Bay, West Greenland, were examined using satellite telemetry. Data on movements, habitat use, and phenology were collected from tagged 49 bowheads and 44 humpbacks during the transition from sea-ice breakup to open water between 2008 and 2010. Bowhead whales began their northward spring migration around 27 May (median day-of-the-year departure date = 147, interquartile range 141–153) and were distributed broadly in northern and central Disko Bay in water depths between 100 and 400 m. Humpback whales arrived in Disko Bay no later than 2 June and were located in shallow water (<100 m) along the coasts of the mainland or Disko Island. Trends in departure date from Disko Bay were significant for bowhead whales (∼15 d later, p < 0.001) between two periods: 2001–2006 and 2008–2010. Many species are predicted to arrive earlier in the Arctic and to expand their range northwards with reduced sea ice and increasing temperatures under climate change. Quantifying the spatial and temporal relationships between co-occurring Arctic and Subarctic top predators allows for baseline insight to be gained on how climate change might alter interspecies interactions.

The effect of decreasing seasonal sea-ice cover on the winter Bering Sea pollock fishery

Citation Information: Pfeiffer, L., and Haynie, A. C. 2012. The effect of decreasing seasonal sea-ice cover on the winter Bering Sea pollock fishery. – ICES Journal of Marine Science, 69:7.

Abstract: The winter fishing season for eastern Bering Sea pollock (Theragra chalcogramma) is during the period of maximum seasonal sea-ice extent, but harvesters avoid fishing in ice-covered waters. Global climate models predict a 40% reduction in winter ice cover by 2050, with potential implications for the costs incurred by vessels travelling to and around their fishing grounds and the value of their catch. Additionally, it may open entirely new areas to fishing. Using retrospective data from 1999 to 2009, a period of extensive annual climate variation, the variation in important characteristics of the fishery is analysed. When ice is present, it restricts a portion of the fishing grounds, but in general, ice-restricted areas have lower expected profits at the time of restriction than the areas left open. Some areas show a change in effort in warm years relative to cold, but the global redistribution of effort attributable to ice cover is small. This is largely because the winter fishery is driven by the pursuit of roe-bearing fish whose spawning location is stable in the southern part of the fishing grounds.

Modelling the abundance of grey seals (Halichoerus grypus) along the Norwegian coast

Citation Information: Øigård, T. A., Frie, A. K., Nilssen, K. T., and Hammill, M. O. 2012. Modelling the abundance of grey seals (Halichoerus grypus) along the Norwegian coast. – ICES Journal of Marine Science, 69:8.

Abstract: An age-structured population dynamics model of the Norwegian grey seal (Halichoerus grypus) population has been developed. The model is of a Bayesian character in the sense that priors for various parameters were used. Model runs indicated an increase in the abundance of the total Norwegian grey seal population during the last 30 years, suggesting a total of 8740 (95% confidence interval: 7320–10 170) animals in 2011. A total catch of 707 (95% confidence interval: 532–882) grey seals would maintain the population size at the 2011 level. Model runs suggest that current catch levels will likely result in a reduction in the population size in Sør-Trøndelag and Nord-Trøndelag counties, and an increase in the population size in Rogaland, Nordland, Troms, and Finnmark counties. The model runs assumed that 80% of the seals taken in Rogaland came from the UK and that 50 and 55% of the catches in Troms and Finnmark, respectively, were immigrants from Russia.

Why economics matters for understanding the effects of climate change on fisheries

Citation Information: Haynie, A. C., and Pfeiffer, L. 2012. Why economics matters for understanding the effects of climate change on fisheries. – ICES Journal of Marine Science, 69:7.

Abstract: Research attempting to predict the effect of climate change on fisheries often neglects to consider how harvesters respond to changing economic, institutional, and environmental conditions, which leads to the overly simplistic prediction of “fisheries follow fish”. However, climate effects on fisheries can be complex because they arise through physical, biological, and economic mechanisms that interact or may not be well understood. Although most researchers find it obvious to include physical and biological factors in predicting the effects of climate change on fisheries, the behaviour of fish harvesters also matters for these predictions. A general but succinct conceptual framework for investigating the effects of climate change on fisheries that incorporates the biological and economic factors that determine how fisheries operate is presented. The use of this framework will result in more complete, reliable, and relevant investigations of the effects of climate change on fisheries. The uncertainty surrounding long-term projections, however, is inherent in the complexity of the system.

Adaptation and maladaptation: factors that influence the resilience of four Alaskan fisheries governed by durable entitlements

Citation Information: Criddle, K. R. 2012. Adaptation and maladaptation: factors that influence the resilience of four Alaskan fisheries governed by durable entitlements. – ICES Journal of Marine Science, 69:7.

Abstract: Sustainability of fisheries and fishery-dependent communities depends largely on the intrinsic characteristics of social, economic, and legal systems that determine who is allowed to fish and how fishing takes place. That is, fisheries sustainability is not a biological problem, it is a social problem. Social factors that contribute to or detract from sustainability are illustrated in four Alaskan fisheries as they have evolved over time. Each fishery has come to be managed under durable entitlements (DEs) in terms of their participation. DE programmes, such as limited entry permits and individual or community fishing quotas, can increase profitability and help fishers adapt to modest adverse changes in stock abundance, ex-vessel prices, or input costs, but the design characteristics of some DE programmes makes them vulnerable to larger perturbations. Moreover, although DE programmes increase choice and therefore resilience from the perspective of individuals, they can increase or decrease the resilience of fishery-dependent communities.

Assessing the sensitivity of seabird populations to adverse effects from tidal stream turbines and wave energy devices

Citation Information: Furness, R. W., Wade, H. M., Robbins, A. M. C., and Masden, E. A. 2012. Assessing the sensitivity of seabird populations to adverse effects from tidal stream turbines and wave energy devices. – ICES Journal of Marine Science, 69:8.

Abstract: Tidal turbines and wave energy devices may affect seabird populations through collision mortality, disturbance and habitat loss. Given the pressures to harness tidal and wave energy, especially in Scottish waters, there is an urgent need to assess population-level impacts on seabird species. With a lack of deployed devices to monitor in areas of importance for seabirds, our approach uses data from scientific literature on seabird ecology and conservation importance likely to influence population vulnerability to “wet renewables” in Scottish waters. At this stage however, we can only infer likely interactions with tidal and wave devices. We identify black guillemot, razorbill, European shag, common guillemot, great cormorant, divers and Atlantic puffin as the species most vulnerable to adverse effects from tidal turbines in Scottish waters. We identify divers as the species most vulnerable to adverse effects from wave energy devices in Scottish waters. Wave energy devices seem likely to represent a lesser hazard to seabirds than tidal turbines, and both forms of energy capture seem likely to represent a lower hazard to seabirds than offshore wind farms (wind-power plants). The indices developed here for Scottish seabird populations could be applied to populations elsewhere. This approach will help in identifying likely impacts of tidal and wave energy deployments on seabirds, and in optimizing deployment of resources for compulsory environmental monitoring.

Climate-related variations in the occurrence and distribution of mackerel (Scomber scombrus) in Icelandic waters

Citation Information: Astthorsson, O. S., Valdimarsson, H., Gudmundsdottir, A., and Óskarsson, G. J. 2012. Climate-related variations in the occurrence and distribution of mackerel (Scomber scombrus) in Icelandic waters. – ICES Journal of Marine Science, 69:7.

Abstract: Based on long-term investigations on sea temperature in Icelandic waters, five climatic periods are defined from the mid-1880s until today. These are a cold period between 1880 and 1920, a warm period between 1921 and 1964, a cold period between 1965 and 1971, one of intermediate conditions (alternating warm and cold) between 1972 and 1995, and finally a warm period from 1996 until today. Mackerel were first reported from Icelandic waters in 1895, were then found intermittently until 1996, and from then appeared almost every year and since 2007 in large numbers in many areas around Iceland. The occurrence of mackerel appears to be confined mainly to warm periods in the North Atlantic Ocean and around Iceland. The unprecedented occurrence and extended distribution of the species began at the onset of the recent warm period during the mid-1990s and, in recent years, 0-group and age 1 mackerel have also been observed in Icelandic waters. This expansion in distribution resulted initially in a bycatch fishery, which then developed into a direct fishery within the Icelandic Exclusive Economic Zone, increasing from ∼1700 t in 2006 to ∼120 000 t in 2009 and 2010.

Comparison of fisheries yield and oceanographic features at the southern boundaries of the western and eastern Subarctic Pacific Ocean

Citation Information: Kim, S., Kang, S., Zhang, C-I., Seo, H., Kang, M., and Kim, J. J. 2012. Comparison of fisheries yield and oceanographic features at the southern boundaries of the western and eastern Subarctic Pacific Ocean. – ICES Journal of Marine Science, 69:7.

Abstract: The ecological characteristics of fish communities were compared at the southern boundaries of the eastern and western Subarctic Pacific, based on oceanography, fishery information, and ecological features. Sea surface temperature (SST) was higher in the western North Pacific (NP) than in the eastern NP, and changes in SST showed regional and temporal alternating patterns. Cool and warm SST regimes were observed in the western NP during the early 1980s and the early 2000s, respectively, compared with warm and cool regimes in the eastern NP. Increasing SSTs were more conspicuous in the western than in the eastern NP. Catches from commercial fisheries were higher in the western NP than in the eastern NP. Small pelagic fish were dominant in the western NP, whereas demersal behaviour was common for fish populations in the eastern NP. Changes in species composition also showed contrasting characteristics between the two regions. In the western NP during the early 1980s, landings were dominated (35.8%) by sardine. After two decades, however, landings consisted of a more diverse species group. In the eastern NP, five species appeared in similar percentages (∼10% each) during the early 1980s, but hake alone made up 36.3% of the landings in the early 2000s.

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