Seasonal and annual cycles in marine small‐scale fisheries (Ilhéus – Brazil)

Fish stock assessment is a crucial tool for resource management. Small‐scale fisheries are often multispecies and multigear. This study focuses on the search for patterns in the Ilhéus small‐scale fishery using landing data from 2000 to 2006 and climatic data. Ocyurus chrysurus and Ephinephelus spp. were the most commonly landed fish. The number of fishing trips was higher in the winter, when winds were weaker and temperatures lower. When the temperature increased, catches of Seriola dumerili were higher. Coryphaena hippurus and some rays were more abundant in the summer in the presence of stronger winds, intense rainfall and higher air temperature. Large catches of Lutjanus spp. and Scomberomorus spp. were obtained in the autumn. There is an annual seasonality in the fishery, with a cyclical landing pattern regardless of the years considered. These results are important in view of climate change, and specific strategies for better fisheries management are recommended.     

Physical variability in Prince William Sound during the SEA Study (1994–98)

From 1994 to 1998, a multidisciplinary ecosystem study (the Sound Ecosystem Assessment) examined the primary physical and biological factors that influence the production of pink salmon and Pacific herring in Prince William Sound (PWS), species that experienced population declines after the 1989 Exxon‐Valdez oil spill. Three physical processes are described that influence ecosystem processes: surface layer stratification; upper layer (<100 m) circulation; and exchange between PWS and the northern Gulf of Alaska (NGOA). Stratification formed first in the PWS nearshore regions in March, and subsequently in the northern central basin in April, primarily due to freshening. The northern stratified layer and the associated zonal density front persisted at least through June, but year‐to‐year differences occurred. In spring and summer, circulation in central PWS could be either cyclonic or anticyclonic. Drifter trajectories often linked central PWS to a nearshore bay or fjord, or one bay or fjord to another. September was characterized by a cyclonic circulation and isopycnal doming in central PWS, with little year‐to‐year variability. At Hinchinbrook Entrance, a main connection with the Gulf of Alaska, alternating inflows and outflows occurred in spring over all depths. In summer through early autumn (1995), in the absence of predominantly westward winds, the dominant exchange pattern was outflow above about 150 m and inflow below. In summer through early autumn (1996–98), there was also surface (<20 m) inflow at Montague Strait (the other main entrance). Northward transport at Hinchinbrook Entrance was maximum in late autumn through winter, with inflow above ~150 m and outflow below. Westward wind events over the shelf associated with the weather cycle drove inflow events at both Hinchinbrook Entrance and Montague Strait that may result in transport of zooplankton important to the PWS ecosystem.     

Historical distribution of the otter (Lutra lutra) in north‐east China according to historical records (1950–2014)

1. The Eurasian otter (Lutra lutra) has undergone a dramatic decline throughout the 20th century in China, especially in the North East. However, the dynamics responsible for the reduction in the distribution of otters in this region since the 1950s is still unclear. Such uncertainty and insufficient information can hinder effective conservation strategies. 2. A study was conducted using historical documents to attempt an evaluation of the status of otter populations in north‐east China between 1950 and 2014. The data suggest that otters were widely distributed with abundant populations in north‐east China in the 1950s, particularly in the area of the Songhua River basin and the Ussuli River basin. 3. Compared with the 1950s, the number of records in 2014 has fallen by 92%. Otter populations are fragmented and mainly restricted to national nature reserves, leaving little optimism for their future. 4. More broadly, this research demonstrates that recovering information from local historical documents can be a useful and reliable way to overcome the limits caused by lack of data. Copyright © 2016 John Wiley & Sons, Ltd.     

Northerly shift of warm‐water copepods in the western subarctic North Pacific: Continuous Plankton Recorder samples (2001–2013)

Spatial and temporal variation in copepod community structure, abundance, distribution and biodiversity were examined in the western subarctic North Pacific (40–53°N, 144–173°E) during 2001–2013. Continuous Plankton Recorder (CPR) observational data during the summer season (June and July) were analyzed. The latitudinal distribution of warm‐water species in June shifted northward after 2011 while no apparent latitudinal shift of cold‐water and other species was observed. Species number and the Shannon–Wiener biodiversity index (H′) in June tended to increase in the northern area after 2011. The warm‐water species abundance and center latitude of warm‐water distribution were positively correlated with sea surface temperature (SST) across sampling locations, whereas no significant correlations with SST were observed for cold‐water species or other species. Warm SSTs in June after 2011 appeared to cause the northward shift of warm‐water species distribution, which in turn contributed to the higher biodiversity in the northern area. This study demonstrated the rapid response of warm‐water species to warm SST variation, whereas cold‐water and other species did not exhibit such clear responses. These findings indicate that the response of copepods to environmental changes differs among copepod species, highlighting the importance of investigating lower trophic levels to the species level to evaluate individual species’ responses to climate change.     

Decreasing shrimp (Pandalus borealis) sizes off Newfoundland and Labrador – environment or fishing?

During the 1990s, carapace length statistics including minimum size caught (L_min), mean male and female lengths, size at sex transition (L₅₀) and maximum size (L_max) of northern shrimp (Pandalus borealis) decreased in commercial and survey catches off Newfoundland and Labrador. Decreased growth rates caused by decreases in per‐capita food availability due to large population increases, exacerbated by increased metabolic demands from higher water temperatures in the mid‐1990s, appear to be the main cause of the size decrease. Fishing could have had an accelerating effect on environmentally driven decreases in shrimp growth and size by ‘cropping’ the largest shrimp from the population. The greatest decreases in shrimp size occurred in Hudson Strait and the adjacent northern shelf, the area which also has the highest densities and largest shrimp. We hypothesize that the greater size decrease here resulted from decreased primary production from decreased nutrient flux into the euphotic zone, caused by increased atmospheric warming, freshwater runoff and stratification during the warming trend of the 1990s.     

Infectious agent detections in archived Sockeye salmon (Oncorhynchus nerka) samples from British Columbia,Canada (1985–94)

In response to concerns that novel infectious agents were introduced through the movement of eggs as Atlantic salmon aquaculture developed in British Columbia (BC), Canada, we estimated the prevalence of infectious agents in archived return‐migrating Sockeye salmon, from before and during aquaculture expansion in BC (1985–94). Of 45 infectious agents assessed through molecular assays in 652 samples, 23 (7 bacterial, 2 viral and 14 parasitic) were detected in liver tissue from six regions in BC. Prevalence ranged from 0.005 to 0.83 and varied significantly by region and year. Agent diversity ranged from 0 to 12 per fish (median 4), with the lowest diversity observed in fish from the Trans‐Boundary and Central Coast regions. Agents known to be endemic in Sockeye salmon in BC, including Flavobacterium psychrophilum, Infectious haematopoietic necrosis virus, Ceratonova shasta and Parvicapsula minibicornis, were commonly observed. Others, such as Kudoa thyrsites and Piscirikettsia salmonis, were also detected. Surprisingly, infectious agents described only recently in BC salmon, Ca. Branchiomonas cysticola, Parvicapsula pseudobranchicola and Paranucleospora theridion, were also detected, indicating their potential presence prior to the expansion of the aquaculture industry. In general, our data suggest that agent distributions may not have substantially changed because of the salmon aquaculture industry.