Prevalence and Risk of Anisakid Larvae in Fresh Fish Frequently Consumed in Spain: An Overview

Anisakidosis is a fish-borne zoonosis caused by parasitic nematodes of the family Anisakidae, of which the species belonging to Anisakis simplex complex are the most representative. It is considered an emerging disease in Spain. The objective of this study is to analyse the presence of larvae in fish frequently consumed in Spanish supermarkets, inferring the risk of infection. In total 1,786 specimens of 9 different fish species, from two geographical origins (Atlantic and Mediterranean), acquired fresh and not eviscerated were examined for anisakid nematodes. Analysis showed that 33.7% of the samples were parasitized by Anisakis larvae. The horse mackerel (Trachurus trachurus) presented the highest total prevalence (66.0%), followed by the silver hake (Merluccius bilinearis) (59.5%), the mackerel (Scomber scombrus) (58.4%), the blue whiting (Micromesistius poutassou) (53.9%) and the European hake (Merlucius merlucius) (45.0%). In general, the prevalence was higher in Atlantic than in Mediterranean fish. In all the species analysed, a higher presence of the parasite was detected in the viscera than in the flesh, although in the most parasitized species a noteworthy prevalence and abundance was observed in the flesh. In conclusion, risk factors, like fish species and origin, should be considered by consumers, in addition of following the recommendations established by Commission Regulation (EU) No1276/2011 and the Spanish Royal Decree 1420/2006.

A zero percent plastic ingestion rate by silver hake (Merluccius bilinearis) from the south coast of Newfoundland, Canada

Silver hake, (Merluccius bilinearis), contributes significant biomass to Northwest Atlantic ecosystems. The incidence of plastic ingestion for 134 individuals collected from Newfoundland, Canada was examined through visual examination of gastrointestinal contents and Raman spectrometry. We found a frequency of occurrence of ingestion of 0%. Through a comprehensive literature review of globally published fish ingestion studies, we found our value to be consistent with 41% (n=100) of all reported fish ingestion rates. We could not statistically compare silver hake results to other species due to low sample sizes in other studies (less than n=20) and a lack of standardized sampling methods. We recommend that further studies should 1) continue to report 0% plastic ingestion rates and 2) should describe location and species-specific traits that may contribute to 0% ingestion rates, particularly in locations where fish consumption has cultural and economic significance.

Reduced herding of flounders by floating bridles: application in Gulf of Maine Northern shrimp trawls to reduce bycatch

We hypothesized that a floating trawl bridle that does not contact the seabed would reduce the herding of fish, especially bottom dwelling flounders, and thus reduce bycatch of these fish in shrimp trawls. We further hypothesized that, due to the non-herding nature of northern shrimp (Pandalus borealis), the use of an off-bottom floating bridle would not reduce shrimp catch. These hypotheses were tested in the field by comparing a trawl with regular bottom-tendering wire bridles and the same trawl with floating synthetic bridles in the Gulf of Maine northern shrimp fishery. As expected, no statistically significant differences in catch rates and size were found for the targeted northern shrimp (146.3 ± 10.58 kg h−1 control vs. 140.8 ± 9.35 kg h−1, p = 0.13). Total finfish bycatch was reduced by 14.9%, and the difference was statistically different (p = 0.01). The most important reduction was the catch of juvenile American plaice (Hippoglossoides platessoides) with a significant reduction of 20.0% (p = 0.01). For witch flounder (Glyptocephalus cynoglossus), a reduction of 19.3% was found, but it was not statistically significant (p = 0.14). The reduction of Acadian redfish (Sebastes fasciatus) (by 28.0%, p = 0.02) was also statistically different. Catch of targeted silver hake (Merluccius bilinearis) was reduced by 10.8%, but the difference was only marginally significant (p = 0.07). An analysis of length frequencies for the targeted shrimp and major bycatch species revealed no size-related selection between the gears with regular bridles and floating bridles. The reductions in flounder bycatch indicate reduced herding of benthic species when the bridles are kept off bottom. This easy modification may be readily adopted in the northern shrimp fisheries in the North Atlantic, and can also possibly be applied in other shrimp and prawn fisheries with further experimentation.

Feeding hotspots for four northwest Atlantic groundfish species

Methratta, E.T., and Link, J.S. 2012. Feeding hotspots for four northwest Atlantic groundfish species. — ICES Journal of Marine Science, 69: 1710–1721. We used predator distribution and stomach content data to estimate the annual per capita rate of consumption for four representative predator species from the northwestern Atlantic Ocean, and considered how consumption is influenced by depth, bottom salinity, sediment grain size, location variables, and species-specific diet components. We found that geographic variables and species-specific prey resources were significantly associated with consumption rates, a pattern consistent with predator-prey theory. Prey categories comprised of fish were particularly important for a more mobile predator (silver hake Merluccius bilinearis), whereas benthic invertebrate prey were consistently important for a more sedentary predator (little skate Raja erinacea). Hotspots in consumption rates that overlap with particular prey resources were highlighted by the significance of location variables (longitude) for winter flounder Pseudopleuronectes americanus, silver hake, little skate, and sea raven Hemitripterus americanus. Depth was an important explanatory factor for consumption by little skate, but the explanatory value of abiotic habitat factors was low for the other three species. Greater emphasis on species-specific food habits, migratory patterns, and ecological interactions at the synoptic scales relevant to fisheries is needed for fisheries management.

Predation of larval benthic invertebrates in St George’s Bay, Nova Scotia

Larval survival during planktonic dispersal is crucial to the connectivity among benthic populations. Although predation has been suggested as an important cause of larval mortality, this process has rarely been quantified in the field. We measured the abundance of various larval species in the water column in St George’s Bay, Nova Scotia, Canada, on 3 different occasions in summer (August 2008, July and August 2009), the period of high larval abundance in our region. We sampled four numerically dominant predators (scyphozoans: Cyanea capillata and Aurelia aurita; fishes: Gasterosteus aculeatus and Merluccius bilinearis) and lobster larvae near the water surface with a neuston net and other larval species in the water column (3 m depth) with a ring net. Larvae found in the gut contents of the predators included various species of gastropods, crustaceans and bivalves, and these were more abundant in the scyphozoans than the fishes. We attribute these differences to variation in predation method. For certain larval taxa, we found significant differences between the proportional abundance in the guts of C. capillata and in the water column, indicating prey selectivity. This study evaluates the potential impact of predation on larval survival and indicates that the presence of predators can cause changes in abundance and consequent taxonomic shifts in species dominance of larvae, influencing their successful subsequent recruitment to the benthos.