Daily and Annual Variation in Digestive Enzymes – Amylase and Basic and Acid Proteases – in Gilt‐head Sea Bream,Sparus aurata

This study examines the daily and annual changes in amylase and basic and acid protease activities in gilt‐head sea bream, Sparus aurata. During the experiment, the fish were kept in cages for production under natural temperature and photoperiod conditions and fed with a commercial diet. To study the effect of photoperiod and temperature, the experiments were conducted during six different months that were chosen based on temperature and photoperiod. To determine daily changes in enzymes activities, for every 3 h during 24 h period, six fish were randomly selected and sacrificed. The annual results for acid protease activity show a rhythm with 6‐mo period (bimodal rhythm) with acrophases in May and November. The activities of pancreatic enzymes, which include basic protease and amylase, exhibited parallel changes with two peaks of activity in January and October without a rhythmic pattern. The daily changes in enzyme activities are significant only in May, June, and November for basic proteases and May, October, and November for amylase (P < 0.05). The observed variations suggest a varying capacity for digestion depending on the day and the year and could aid in the study of seasonal feeding protocols.     

Piscine reovirus in wild and farmed salmonids in British Columbia,Canada: 1974–2013

Piscine reovirus (PRV) was common among wild and farmed salmonids in British Columbia, western Canada, from 1987 to 2013. Salmonid tissues tested for PRV by real‐time rRT‐PCR included sections from archived paraffin blocks from 1974 to 2008 (n = 363) and fresh‐frozen hearts from 2013 (n = 916). The earliest PRV‐positive sample was from a wild‐source steelhead trout, Oncorhynchus mykiss (Walbaum), from 1977. By histopathology (n = 404), no fish had lesions diagnostic for heart and skeletal muscle inflammation (HSMI). In some groups, lymphohistiocytic endocarditis affected a greater proportion of fish with PRV than fish without PRV, but the range of Ct values among affected fish was within the range of Ct values among unaffected fish. Also, fish with the lowest PRV Ct values (18.4–21.7) lacked endocarditis or any other consistent lesion. From 1987 to 1994, the proportion of PRV positives was not significantly different between farmed Atlantic salmon, Salmo salar L. (44% of 48), and wild‐source salmonids (31% of 45). In 2013, the proportion of PRV positives was not significantly different between wild coho salmon, Oncorhynchus kisutch (Walbaum), sampled from British Columbia (5.0% of 60) or the reference region, Alaska, USA (10% of 58).     

The sharks of South East Asia – unknown,unmonitored and unmanaged

Sharks fisheries have declined globally due to over‐ and unregulated fishing. As with many collapsed and unmonitored coastal fisheries, information is difficult to obtain, yet it is important to understand the historical changes determining population trends and evaluate the current status of sharks in order to conserve these vulnerable species. Here, we document for the first time the history and general condition of the shark fisheries of Southern China, specifically Hong Kong, and Guangdong, Fujian and Hainan Provinces. This study shows, through the use of historical literature and anecdotal accounts, including fisher interviews, that all known shark fisheries in the region collapsed between the 1970s and the 1990s. Of the 109 species present historically in the South China Sea, only 18 species were recorded in current market surveys, of which all were landed as bycatch and 65% were below the size of sexual maturity. Markets are dominated by smaller species, including the spadenose shark (Scoliodon laticaudus) and the whitespotted bambooshark (Chiloscyllium plagiosum). Marketed large shark species are almost all below the size of sexual maturation, evidence of growth overfishing and a factor in recruitment overfishing. Some species, like the whale (Rhincodon typus) and basking sharks (Cetorhinus maximus), are clearly vulnerable to local extinction without intervention. Given the inherent vulnerability of sharks and the overfished states of many sharks, there is clearly an urgent need to formulate impacting conservation and management plans for these rapidly declining species in a region that has the highest demand for shark products globally.     

Infectious salmon anaemia – pathogenesis and tropism

Infectious salmon anaemia (ISA) is a serious disease of farmed Atlantic salmon caused by the aquatic orthomyxovirus infectious salmon anaemia virus (ISAV). ISA was first detected in Norway in 1984 and was characterized by severe anaemia and circulatory disturbances. This review elucidates factors related to the pathogenesis of ISA in Atlantic salmon, the dissemination of the virus in the host and the general distribution of the 4‐O‐acetylated sialic acids ISAV receptor. The knowledge contributes to the understanding of this disease, and why, almost 30 years after the first detection, it is still causing problems for the aquaculture industry.     

Accelerated extractions of North Atlantic cod and herring, 1520–1790

We propose the concept of Accelerated Marine Extraction to signify two periods when rapidly increasing cod (Gadus morhua, Gadidae) and herring (Clupea harengus, Clupeidae) fisheries, c.1540–1600 and c. 1730–1790, exceeded human demographic growth. Total landings vastly exceeded previous assessments and more than doubled between 1520 and 1620 from about 220,000 metric tonnes (t) to 460,000 t. Supplies of cod and herring to the European market peaked in 1788 at more than 1 million t before the unrest connected with the French Revolution brought many fisheries to a temporary halt. Accelerated Marine Extractions increased European food security at times of human demographic growth by almost doubling the supplies of fish protein per capita. While herring was the most important species by 1520, cod dominated through the period 1540–1790, and the trajectories of cod and herring extractions differed significantly. Cod landings increased almost ten-fold between 1520 and 1790, driven by strong and sustained landings in the Northwest Atlantic. Herring landings remained stable through the 16th century but declined severely through the next 150 years. However, from 1750, herring landings quadrupled, largely because of Swedish west coast fisheries. The results fundamentally shift our understanding of the scale of Atlantic fisheries in the past and underline the role of marine resources for European societies.     

Sawfishes in The Gambia and Senegal – shifting baselines over 40 years

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