Fisheries Oceanography: The first 30 years and new challenges in the 21st century

The journal Fisheries Oceanography provides a global forum for fisheries scientists and oceanographers to understand how marine ecosystems, and the services they provide to society, are structured and shaped by environmental variability and climate change. With this special issue, as well as the 30th Anniversary Virtual Issue of the most influential papers from the journal's history, we commemorate 30 years of publishing leading research in the field of fisheries oceanography. These issues showcase the extent, depth and impact of the research published in Fisheries Oceanography. We also reflect on the evolution of research themes through the journal's history, and highlight key emergent themes in our field. We look forward to continuing to publish impactful research in the pages of Fisheries Oceanography in the years ahead.     

Narrow lenses for capturing the complexity of fisheries: A topic analysis of fisheries science from 1990 to 2016

Despite increased fisheries science output and publication outlets, the global crisis in fisheries management is as present as ever. Since a narrow research focus may be a contributing factor to this failure, this study uncovers topics in fisheries research and their trends over time. This interdisciplinary research evaluates whether science is diversifying fisheries research topics in an attempt to capture the complexity of the fisheries system, or whether it is multiplying research on similar topics, attempting to achieve an in‐depth, but possibly marginal, understanding of a few selected components of this system. By utilizing latent Dirichlet allocation as a generative probabilistic topic model, we analyse a unique dataset consisting of 46,582 full‐text articles published in the last 26 years in 21 specialized scientific fisheries journals. Among the 25 topics uncovered by the model, only one (Fisheries management) refers to the human dimension of fisheries understood as socio‐ecological complex adaptive systems. The most prevalent topics in our dataset directly relating to fisheries refer to Fisheries management, Stock assessment, and Fishing gear, with Fisheries management attracting the most interest. We propose directions for future research focus that most likely could contribute to providing useful advice for successful management of fisheries.     

Warm oceans exacerbate Chinook salmon bycatch in the Pacific hake fishery driven by thermal and diel depth-use behaviours

Fisheries bycatch impacts marine species globally and understanding the underlying ecological and behavioural mechanisms could improve bycatch mitigation and forecasts in novel conditions. Oceans are rapidly warming causing shifts in marine species distributions with unknown, but likely, bycatch consequences. We examined whether thermal and diel depth-use behaviours influenced bycatch of a keystone species (Chinook salmon; Oncorhynchus tshawytscha, Salmonidae) in the largest fishery on the US West Coast (Pacific hake; Merluccius productus, Merlucciidae) with annual consequences in a warming ocean. We used Generalized Additive Models with 20 years of data including 54,509 hauls from the at-sea hake fishery spanning Oregon and Washington coasts including genetic information for five salmon populations. Our results demonstrate that Chinook salmon bycatch rates increased in warm ocean years explained by salmon depth-use behaviours. Chinook salmon typically occupy shallower water column depths compared to hake. However, salmon moved deeper when sea surface temperatures (SSTs) were warm and at night, which increased overlap with hake and exacerbated bycatch rates. We show that night fishing reductions (a voluntary bycatch mitigation strategy) are effective in reducing salmon bycatch in cool SSTs by limiting fishing effort when diel vertical movements bring salmon deeper but becomes less effective in warm SSTs as salmon seek deeper thermal refugia during the day. Thermal and diel behaviours were more pronounced in southern compared with northern salmon populations. We provide mechanistic support that climate change may intensify Chinook salmon bycatch in the hake fishery and demonstrate how an inferential approach can inform bycatch management in a changing world.     

Ecosystem-based psychology, or, how I learned to stop worrying and love the data

The emerging fisheries science paradigm may be drifting in what some applied fisheries scientists consider an intractable assignment – Ecosystem-Based Fisheries Management (EBFM) or the Ecosystem Approach to Fisheries (EAF). In this paper I suggest that the lack of progress in implementing EBFM-EAF is partly psychological and that the multidisciplinary approach to it should include psychology, a discipline that has largely ignored the overwhelming problems of fisheries management.     

Time‐varying relationships between ocean conditions and sockeye salmon productivity

Environmental change is occurring at unprecedented rates in many marine ecosystems. Yet, environmental effects on fish populations are commonly assumed to be constant across time. In this study, I tested whether relationships between ocean conditions and productivity of North American sockeye salmon (Oncorhynchus nerka) stocks have changed over the past six decades. Specifically, I evaluated the evidence for non‐stationary relationships between three widely used ocean indices and productivity of 45 sockeye salmon stocks using hierarchical Bayesian models. The ocean indices investigated were the Pacific Decadal Oscillation (PDO), North Pacific Gyre Oscillation (NPGO), and sea surface temperature (SST). I found partial support for time‐varying salmon–ocean relationships. Non‐stationary relationships were strongest for the NPGO and weaker for the SST and PDO indices. Productivity–NPGO correlations tended to shift gradually over time with opposite trends for stocks in British Columbia (B.C.) and western Alaska; for B.C. stocks, the NPGO correlations shifted from significantly negative prior to 1980 to significantly positive after 1990, whereas for western Alaska stocks, the correlations shifted from positive to negative. Productivity–SST correlations showed declining trends for B.C. and Gulf of Alaska stocks, that is, correlations became more negative (B.C.) or less positive (Gulf of Alaska) over time. For the PDO, correlations weakened during the 1980s for western Alaska and B.C. stocks. Overall, these results provide evidence for time‐varying relationships between salmon productivity and environmental conditions over six decades, highlighting the need to recognize that historical responses of salmon populations to environmental change may not be indicative of future responses.     

Influences of ocean conditions and feeding ecology on the survival of juvenile Chinook Salmon (Oncorhynchus tshawytscha)

Recruitment variability in many fish populations is postulated to be influenced by climatic and oceanographic variability. However, a mechanistic understanding of the influence of specific variables on recruitment is generally lacking. Feeding ecology is one possible mechanism that more directly links ocean conditions and recruitment. We test this mechanism using juvenile Chinook Salmon (Oncorhynchus tshawytscha) collected off the west coast of Vancouver Island, British Columbia, Canada, in 2000–2009. Stable isotopes of carbon (δ¹³C), an indicator of temperature or primary productivity, and nitrogen (δ¹⁵N), an indicator of trophic position, were taken from muscle tissues of genetically stock‐identified salmon. We also collated large‐scale climate indices (e.g., Pacific Decadal Oscillation, North Pacific Gyre Oscillation), local climate variables (e.g., sea surface temperature) and copepod community composition across these years. We used a Bayesian network to determine how ocean conditions influenced feeding ecology, and subsequent survival rates. We found that smolt survival of Chinook Salmon is predicted by their δ¹³C value, but not their δ¹⁵N. In turn, large‐scale climate variability determined the δ¹³C values of salmon, thus linking climate to survival through feeding ecology, likely through qualities propagated from the base of the food chain.     

A century and a half of change in the climate of the NE Pacific

Spectral analysis of twenty-one climate records indicates that NE Pacific temperatures and winter wind stress have fluctuated at four dominant time scales in this century: 2–3 years (quasi-biennial oscillation), 5–7 years (El Nio-Southern Oscillation, ENSO), 20–25 years (bidecadal oscillation, BDO), and a poorly resolved, very-low-frequency (VLF) oscillation with a 50–75 year period. Forty-four per cent of the low-frequency variability in British Columbia air temperatures is associated with the strength of the Aleutian Low pressure system in winter. Only 42% of the 'strong' and 25% of the 'moderate' ENSO events in this century have produced large warm anomalies off BC. Interactions between the ENSO, bidecadal and very-low-frequency oscillations produce a pattern of alternating warm and cool climate states, with major warnings every 50 to 75 years. Since 1850 there have been seven warm periods, lasting an average of 11.4 years, and six cool periods lasting an average of 10.8 years. Sharp transitions from cool to warm climate states (as in 1977/78) occur when warming phases of the BDO and VLF oscillations coincide. Recent evidence suggests that the BDO may originate in either the tropical or the subtropical North Pacific. The NE Pacific has experienced a major warming since 1978. A long-range forecast suggests that the BDO and VLF oscillations peaked in 1989 and are currently in a cooling phase. Consequently, coastal temperatures should moderate for the rest of this century. A transition to the next cool climate state could occur about the year 2001. The forecast for moderating temperatures could begin the first phase of the recovery of the southern BC coastal chinook and coho salmon and herring stocks, which are currently at low abundance levels.     

Providing context to the global code of practice for recreational fisheries

Abstract An in‐depth explanation of selected content of the European Inland Fisheries Advisory Commission’s ‘Code of Practice for Recreational Fisheries’ (CoP) is presented. The focus is on core areas that were intensely debated in the drafting the CoP. These include definition of recreational fishing, recreational fishing practices, fish welfare, recreational fisheries management and research. It is anticipated that the CoP for recreational fisheries promotes best practice and management principles for sustainable recreational fisheries, within the recreational fisheries sector and ancillary industries/sectors regionally, nationally, and ultimately globally. To be viable, the CoP for recreational fisheries must be adopted by the international community complementing the Code of Conduct for Responsible Fisheries of the Food and Agriculture Organization of the United Nations.     

福建省渔业工程与装备学科发展报告

渔业工程与装备是渔业生产现代化水平的重要标志之一，也是推进渔业生产方式转变的重要途径，是现代渔业科技不可或缺的重要组成。本文报道了福建省近年来所涉及的渔业工程与装备学科的发展现状，包括陆基养殖、港湾鱼类及鲍网箱养殖、深水区抗风浪网箱养殖、微孔增氧技术、湿颗粒饲料加工机械、大型网箱养殖安全监控技术、新型锚技术开发、闭式循环活鱼运输船、浮筏式消波堤、人工鱼礁、休闲渔业和风（能）光（太阳能）互补型海水淡化装置等。分析学科目前存在的问题并提出中期发展目标及“十二五”主攻方向。     

A survey of microparasites present in adult migrating Chinook salmon (Oncorhynchus tshawytscha) in south‐western British Columbia determined by high‐throughput quantitative polymerase chain reaction

Microparasites play an important role in the demography, ecology and evolution of Pacific salmonids. As salmon stocks continue to decline and the impacts of global climate change on fish populations become apparent, a greater understanding of microparasites in wild salmon populations is warranted. We used high‐throughput, quantitative PCR (HT‐qRT‐PCR) to rapidly screen 82 adult Chinook salmon from five geographically or genetically distinct groups (mostly returning to tributaries of the Fraser River) for 45 microparasite taxa. We detected 20 microparasite species, four of which have not previously been documented in Chinook salmon, and four of which have not been previously detected in any salmonids in the Fraser River. Comparisons of microparasite load to blood plasma variables revealed some positive associations between Flavobacterium psychrophilum, Cryptobia salmositica and Ceratonova shasta and physiological indices suggestive of morbidity. We include a comparison of our findings for each microparasite taxa with previous knowledge of its distribution in British Columbia.     

Covariation between the average lengths of mature coho (Oncorhynchus kisutch) and Chinook salmon (O. tshawytscha) and the ocean environment

We used the average fork length of age‐3 returning coho (Oncorhynchus kisutch) and age‐3 ocean‐type and age‐4 stream‐type Chinook (Oncorhynchus tshawytscha) salmon along the northeast Pacific coast to assess the covariability between established oceanic environmental indices and growth. These indices included the Multivariate El Niño‐Southern Oscillation Index (MEI), Pacific Decadal Oscillation (PDO), Northern Oscillation Index, and Aleutian Low Pressure Index. Washington, Oregon, and California (WOC) salmon sizes were negatively correlated with the MEI values indicating that ultimate fish size was affected negatively by El Niño‐like events. Further, we show that the growth trajectory of WOC salmon was set following the first ocean winter. Returning ocean‐type British Columbia‐Puget Sound Chinook salmon average fork length was positively correlated with the MEI values during the summer and autumn of return year, which was possibly a result of a shallower mixed layer and improved food‐web productivity of subarctic Pacific waters. Size variation of coho salmon stocks south of Alaska was synchronous and negatively correlated with warm conditions (positive PDO) and weak North Pacific high pressure during ocean residence.     

Forecasting climate-induced changes in the survival of Snake River spring/summer Chinook salmon (Oncorhynchus tshawytscha)

Effective conservation and management of natural resources requires accurate predictions of ecosystem responses to future climate change, but environmental science has largely failed to produce these reliable forecasts. The future response of Pacific salmon (Oncorhynchus spp.) to a changing environment and continued anthropogenic disturbance is of particular interest to the public because of their high economic, social, and cultural value. While numerous retrospective analyses show a strong correlation between past changes in the ocean environment and salmon production within the north Pacific, these correlations rarely make good predictions. Using a Bayesian time-series model to make successive 1-yr-ahead forecasts, we predicted changes in the ocean survival of Snake River spring/summer chinook salmon (O. tshawytscha) from indices of coastal ocean upwelling with a high degree of certainty (R² = 0.71). Furthermore, another form of the dynamic times-series model that used all of the available data indicated an even stronger coupling between smolt-to-adult survival and ocean upwelling in the spring and fall (R² = 0.96). This suggests that management policies directed at conserving this threatened stock of salmon need to explicitly address the important role of the ocean in driving future salmon survival.     

Conservation status of eulachon in the California Current

Eulachon (Thaleichthys pacificus), an anadromous smelt in the Northeast Pacific Ocean was examined for listing under the USA’s Endangered Species Act (ESA). A southern Distinct Population Segment (DPS) of eulachon – that occurs in the California Current and is composed of numerous subpopulations that spawn in rivers from northern California to northern British Columbia – was identified on the basis of ecological and environmental characteristics, and to a lesser extent, genetic and life history variation. Although the northern terrestrial boundary of this DPS remains uncertain, our consensus opinion was that this northern boundary occurs south of the Nass River and that the DPS was discrete from more northern eulachon, as well as significant to the biological species as a whole and thus is a ‘species’ under the ESA. Eulachon have been nearly absent in northern California for over two decades, have declined in the Fraser River by over 97% in the past 10 years, and are at historically low levels in other British Columbia rivers in the DPS, and nearly so in the Columbia River. Major threats to southern eulachon include climate change impacts on ocean and freshwater habitat, by‐catch in offshore shrimp trawl fisheries, changes in downstream flow timing and intensity owing to dams and water diversions, and predation. These threats, together with large declines in abundance, indicate that the southern DPS of eulachon is at moderate risk of extinction throughout all of its range. The southern DPS was listed as threatened under the ESA in May 2010 – the first marine forage fish to be afforded these statutory protections, which apply only to waters under U.S. jurisdiction.     

国内外渔业信息化发展现状对比分析

渔业信息化是实现渔业现代化的一个重要支撑条件，将主导未来渔业现代化的发展方向。本文对比分析了国内外渔业基础数据库、渔业信息网络建设与开发、地球空间信息科学技术和人工智能技术在渔业中的应用这四个方面的发展情况，指出我国目前渔业信息化发展存在的问题，并提出今后我国渔业信息化发展的建议，认为我国渔业信息化发展要在差距中明确发展战略，在战略中谋求发展。     

Evaluation of juvenile salmon behavior at Bonneville Dam,Columbia River,using a multibeam technique

In recent years, with increased effort to bypass and guide fragile stocks of juvenile salmon in the Columbia Basin past hydroelectric projects, it has been increasingly important to obtain fine-scale fish behavior data in a non-intrusive manner. The Dual-Head Multibeam Sonar is an emerging technology for fisheries applications that addresses that requirement. It has two principal advantages over traditional hydroacoustic techniques: 1) it allows for simultaneous large-volume coverage of a region of interest, and 2) it affords three-dimensional tracking capability. The use of Dual-Head Multibeam Sonar in this study resulted in an unprecedented insight into fine-scale smolt behavior upstream of a prototype surface collector at the Bonneville Dam first powerhouse in 1998. Our results indicated that outmigrant juvenile salmon had an increased likelihood of milling or holding. This discovery will lead to better design criteria for future bypass and collector systems. Future fisheries multibeam sonar systems will likely be fully integrated systems with built-in real-time tracking capability. These systems may be used to track targets relative to physical guidance structures or other behavior-modifying stimuli such as light, turbulent flow, electrical/magnetic fields, or low-frequency sound and vibration. The combination of fine-scale fish behavior data and environmental parameters will yield better design criteria for the safe passage of listed or endangered species of Pacific salmon.     

Effects of the North Pacific Current on the productivity of 163 Pacific salmon stocks

Horizontal ocean transport can influence the dynamics of higher‐trophic‐level species in coastal ecosystems by altering either physical oceanographic conditions or the advection of food resources into coastal areas. In this study, we investigated whether variability in two North Pacific Current (NPC) indices was associated with changes in productivity of North American Pacific salmon stocks. Specifically, we used Bayesian hierarchical models to estimate the effects of the north‐south location of the NPC bifurcation (BI) and the NPC strength, indexed by the North Pacific Gyre Oscillation (NPGO), on the productivity of 163 pink, chum, and sockeye salmon stocks. We found that for salmon stocks located in Washington (WA) and British Columbia (BC), both the BI and NPGO had significant positive effects on productivity, indicating that a northward‐shifted bifurcation and a stronger NPC are associated with increased salmon productivity. For the WA and BC regions, the estimated NPGO effect was over two times larger than the BI effect for pink and chum salmon, whereas for sockeye salmon the BI effect was 2.4 times higher than the NPGO. In contrast to WA and BC stocks, we found weak effects of both horizontal ocean transport processes on the productivity of salmon stocks in Alaska. Our results indicated that horizontal transport pathways might strongly influence population dynamics of Pacific salmon in the southern part of their North American ranges, but not the northern part, suggesting that different environmental pathways may underlie changes in salmon productivity in northern and southern areas for the species under consideration.     

Differences in stability effects on the marine survival of hatchery pink salmon (Oncorhynchus gorbuscha) within the upwelling and downwelling domains of the northeast Pacific Ocean

Regional coastal conditions have a strong influence on juvenile salmon survival during their critical first months in the marine environment. Salmon (genus Oncorhynchus) survival has been thought to be favored within the high latitude downwelling domain if water column stabilities increase, whereas stability may have the opposite effect in upwelling‐dominated lower latitudes. In this study, the relationships between water column stabilities during early marine residence of pink salmon (Oncorhynchus gorbuscha) in both the upwelling and downwelling domains of the northeast Pacific Ocean and marine survival rates for hatchery stocks ranging from Vancouver Island, British Columbia, to Kodiak Island, Alaska, were explored. Contrary to expectation, there was no clear difference in the effect of stability on marine survival rates in the downwelling and upwelling domains. In both domains, marine survival rates increased for pink salmon stocks that experienced below‐average stability on the inner shelf during early marine residence. Stability effects from the outer shelf showed no consistent relationship to marine survival within the northeast Pacific.     

The development of recruitment fisheries oceanography in the United States

Recruitment fisheries oceanography studies the impact of the environment on the annual production of young to fished populations (finfish as well as invertebrates). Interannual variation in recruitment is the most important source of biological variability facing fisheries managers. Because most variation in recruitment occurs during early, mainly planktonic stages, recruitment fisheries oceanography usually integrates studies of plankton and physical oceanography. The concepts upon which these studies rest were first expressed in the late 1800s by Spencer Fullerton Baird, the first Commissioner of the US Commission of Fish and Fisheries. These concepts appear to have been independently developed by Johan Hjort and others in northern Europe in the early 1900s, and brought back to the United States through contacts between Hjort and Henry Bryant Bigelow, who passed the ideas to his students at Harvard University, including Lionel Albert Walford and Oscar Elton Sette. Although both Walford and Sette did their initial work in recruitment fisheries oceanography off the US east coast, as federal fisheries scientists, they were sent to California in response to the decline of the sardine fishery, where they incorporated the ideas of Hjort into the programme that has become the California Cooperative Oceanic Fisheries Investigations (CalCOFI). The original plan for CalCOFI research was to provide a test of Hjort's ideas. Scientists working with CalCOFI implemented this plan and conducted subsequent research that had its roots in the ideas expressed by Baird. This research was in marked contrast to the fishery-yield orientation of most fisheries research that was being conducted at the time on the west coast of North America, under the dominating influence of William Francis Thompson. In recent years, federal fisheries programmes have investigated recruitment processes of a number of other fish stocks, and considerable effort has been expended toward refining the conceptual framework beyond the hypotheses of Hjort. This paper expands on this history, making note of scientists who were particularly important in the evolution of this discipline. We conclude that although recruitment fisheries oceanography has become a well-established field of study, and many technological advances have been made, the recruitment process is still not well understood and fluctuations in year-class abundance remain a major source of uncertainty in managing marine fisheries.     

Ichthyophonus hoferi Plehn & Mulsow in British Columbia stocks of Pacific herring, Clupea pallasi Valenciennes, and its infectivity to chinook salmon, Oncorhynchus tshawytscha (Walbaum)

Pacific herring, Clupea pallasi Valenciennes, collected from three areas of coastal British Columbia were screened for Ichthyophonus by histological examination. The infectivity of Ichthyophonus to juvenile chinook salmon, Oncorhynchus tshawytscha (Walbaum), was examined in laboratory studies. Ichthyophonus was detected in a total of 82 of 356 herring from all three areas. Prevalence in 2000 and 2001 ranged from 10.5 to 52.5% and was significantly lower in more northern (Hecate Strait) samples. Ichthyophonus was detected by histological examination in chinook salmon following oral or intraperitoneal (i.p.) exposure to homogenates of infected herring tissue. Infections in Yukon stock chinook salmon were occasionally associated with mortality and with inflammation in all tissues examined. Infections were detected significantly more frequently in the caecal mesenteries of i.p.-infected compared with oral-infected chinook salmon. The distribution and prevalence of Ichthyophonus isolates among diverse host species may assist in stock identification and in an improved understanding of trophic interactions.