Genetic differentiation between inshore and offshore populations of northern shrimp (Pandalus borealis)

Many marine organisms have a permanent presence both inshore and offshore and spawn in multiple areas, yet their status as separate populations or stocks remain unclear. This is the situation for the northern shrimp (Pandalus borealis) around the Arctic Ocean, which in northern Norway represents an important income for a small-scale coastal fishery and a large-vessel offshore fleet. In Norwegian waters, we uncovered two distinct genetic clusters, viz. a Norwegian coastal and a Barents Sea cluster. Shrimps with a mixed heritage from the Norwegian coastal and the Barents Sea clusters, and genetically different from both, inhabit the fjords at the northernmost coast (Finnmark). Genetic structure between fjords did not display any general trend, and only the Varangerfjord in eastern Finnmark displayed significant genetic structure within the fjord. Shrimps in the Finnmark fjords differed in some degree from shrimps both in the adjacent Barents Sea and along the rest of the coast and should probably be considered a separate management unit.

Northern shrimp Pandalus borealis population collapse linked to climate-driven shifts in predator distribution

The northern shrimp (Pandalus borealis Krøyer) population in the Gulf of Maine collapsed during an extreme heatwave that occurred across the Northwest Atlantic Ocean in 2012. Northern shrimp is a boreal species, and reaches its southern limit in the Gulf of Maine. Here we investigate proximate causes for the population collapse using data from fishery-independent surveys, environmental monitoring, and the commercial fishery. We first examined spatial data to confirm that the decline in population estimates was not due to a major displacement of the population, and then tested hypotheses related to fishing mortality and shifts in predation pressure. Fishing mortality may have contributed but could not explain the magnitude of the decline or the disappearance of pre-exploitable size individuals. Stomach contents analysis and biomass trends revealed no new fish predators of shrimp. However, longfin squid (Doryteuthis pealeii Lesueur) was unique among all species in showing time-series biomass peaks during spring, summer and fall of 2012, and spatial overlap with northern shrimp was unusually high in 2012. Longfin squid is a voracious and opportunistic predator that consumes crustaceans as well as fish. We hypothesize that the warmer temperatures of 2012 not only led to expansion of longfin squid distribution in Gulf of Maine, but had differential effects on migration phenology that further increased spatial overlap with northern shrimp. The weight of our evidence suggests that longfin squid predation was likely a significant factor in the collapse of northern shrimp in the Gulf of Maine.

HISTORY OF THE STUDY AND FEATURES OF THE NORTHERN SHRIMP PANDALUS BOREALIS FISHERY IN THE NORTHERN PART OF THE SEA OF OKHOTSK

The article deals with the history of the study of the northern shrimp, which lives in the northern part of the Sea of Okhotsk. Based on the materials collected in 2020, in comparison with 2018-2019, the course of fishing and catching of this object is analyzed. It is shown that the prospects of industrial development of this valuable object in the coming years do not cause concerns.

Artificial light improves size selection for northern shrimp (Pandalus borealis) in trawls

Size selection in the northern shrimp (Pandalus borealis) trawl fisheries is a widely studied topic. While the focus has largely been on codend and grid selectivity, studies have shown the importance of other design changes and the application of artificial light to evoke behavioural responses. LED lights of three different colours; green (~470–580 nm), white (~425–750 nm) and red (~580–670 nm), were mounted in the belly section of a shrimp trawl to investigate their influence on the overall selectivity of the trawl. The study was conducted using a twin-trawl setup, one with light and the other without light. For catch-comparison analysis, a polynomial regression with random effects was applied. The number of valid hauls with green, white and red lights were eleven, eight, and nine, respectively. All lights tested significantly affected the length-dependent retention of shrimp. Green light had the greatest effect, red the least. Significant loss was observed for shrimp below 17.5 mm carapace length (CL) for green light, 19.5 mm CL for white and 20.8 mm CL for red light.

Using Stated Preference Valuation to Support Sustainable Marine Fishery Management

This study uses a random parameters logit (RPL) model to estimate the Taiwanese preference for northern shrimp (NS) products (NSP) with the Marine Stewardship Council (MSC) label. The estimated results show that, ceteris paribus, the marginal willingness to pay (MWTP) of Taiwanese consumers for NSP with the MSC label is up to New Taiwan dollar (NTD) 84.86 in comparison to products without the label. Moreover, the price of MSC-labeled NSP has a positive effect on the quantity demanded by Taiwanese consumers. They also prefer products in smaller packages and with shorter certification periods. The positive effect can be explained by the Veblen effect or the fact that sometimes prices are perceived as signals of product quality. However, the effects of preference for smaller packages and shorter certification periods are minimal compared with the effects of preference for MSC-labeled products. When consumers are unfamiliar with products or labels, a high price is a viable marketing strategy. However, the advantage cannot sustain the promotion of products and labels.

Cold-water shellfish as harvestable resources and important ecosystem players

The symposium, Shellfish—Resources and Invaders of the North, took place 5–7 November 2019 in Tromsø, Norway. Approximately 110 participants presented and discussed 60 talks and 25 posters. Of these, ten articles are published in this symposium issue. The goal of this symposium was to discuss the role of shellfish, both as harvestable resources and as important ecosystem players in northern hemisphere cold marine environments. To provide perspective for the symposium, the development of four major crustacean fisheries (northern shrimp, snow crab, Homarus, Norway lobster) are reviewed. Our review showed that landings of all these fisheries are still in a state of flux due to inherent population dynamics, fishing, and climate change. The talks and posters covered a broad range of state-of-the-art bioecological knowledge and present challenges in the assessment and management of the most ecologically and/or commercially important cold-water shellfish species belonging to the phyla Arthropoda, Mollusca, and Echinodermata. Various alternative harvesting and management techniques were presented along with perspectives for shellfish aquaculture. Methods and models for stock assessment were thoroughly covered as well as the ecological role of shellfish, their population dynamics, new insights into their biology and genetics, and their changing distribution and significance as invasive species.