Helen Dobby

Marine Scotland

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Co-Authors

Ivone Figueiredo

University of Aveiro

Eskild Kirkegaard

International Council for the Exploration of the Sea

Aaron Hatcher

Broad Institute

Christoph Stransky

Hochschule Bremerhaven

Fabienne Daurès

California Maritime Academy

Tore Gustavsson

Swedish National Board of Fisheries

Jordi Abellà

Universitat Ramon Llull

Didier Gascuel

Institut Agro Rennes-Angers

Ralf Döring

Hochschule Bremerhaven

Sarah Kraak

Johann Heinrich von Thünen-Institut

Cooperative Institutions

Marine Scotland

Norwegian Institute of Marine Research

Centre for Environment, Fisheries and Aquaculture Science

Technical University of Denmark

University of Aberdeen

Marine Institute

Ifremer

Instituto Español de Oceanografía

Wageningen University & Research

Danish Centre for Marine Research

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The potential impact of commercial fishing activity on the ecology of deepwater chondrichthyans from the west of Scotland

Emma Jones Doug Beare Helen Dobby Nolwenn Trinkler Finlay Burns

Since the 1970s the deepwater shelf edge habitat west of the British Isles has been targeted by commercial fishers. The fishery is aimed at teleosts such as ling, black scabbardfish and roundnose grenadier. A smaller component of the catch is, however, composed of Chondrichthyes, i.e. the elasmobranchs (skates & rays) and holocephalans (chimaeras). Until the early 1990s these were discarded, but now they are either actively targeted or retained as by-catch and landed for human consumption. Elasmobranchs are particularly sensitive to high harvesting levels because of slow growth rates, high longevity and low fecundity. A recent combined assessment by ICES of the two most important commercial species, Centroscymnus coelolepis and Centrophorus squamosus indicated drastic decline to less than 50% original biomass. However, landings data are unreliable and fisheries independent, species-specific data that might be used to quantify the effects of fishing in these areas are sparse because of the technological challenges and expense involved in fishing to these depths. In this study, data from scientific deepwater trawl surveys collected by FRS Marine Laboratory were carried out from 1998-2004 and interrogated. These data were examined for any evidence of a decline in abundance and compared with published data from MAFF surveys in the same region between 19701978. Despite the short time series there were indications of declining trends in CPUE for a number of Squaliformes between 1998 and 2004 and the overall catch rates of sharks are dramatically lower than those recorded from pre-exploitation surveys in the 1970s. These results highlight the need to continue fisheries-independent surveys of this vulnerable ecosystem.

Chondrichthyes

Discards

Bycatch

Overfishing

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Citations (7)

Testing length-based reference points in a management strategy evaluation for cuckoo ray (Leucoraja naevus) and thornback ray (Raja clavata)

ICES Journal of Marine Science (2021)

Tanja Miethe Helen Dobby

Abstract Elasmobranchs grow relatively slowly and mature at a relatively high age, leading to longer generation time. Due to low fecundity of these stocks, sufficient numbers of mature individuals are important to ensure a viable recruitment level and sustainable management. Length-based indicators (LBIs), such as the mean length and the mean length of the largest 5% in the catch, can be used to characterize the length distribution of exploited stocks and aid a data-limited assessment. Reference points for these indicators are calculated using basic life history parameters. Using cuckoo ray, Leucoraja naevus, and thornback ray, Raja clavata, as example species, we apply management strategy evaluations to test the performance of LBI-based harvest control rules (HCRs) in their ability to recover overexploited stocks. We illustrate the importance of the stock–recruitment relationship for the management outcome. If immature individuals are targeted by the fishery, HCRs perform better in terms of stock recovery when coupled with reference points, which account for the maturation schedule of the stock. The sensitivity of reference points to parameter misspecification means that elasmobranchs stocks in which immature individuals are exploited by the fishery may require more precautionary reference points, with consideration of the trade-off between biomass recovery and yield.

Stock (firearms)

Stock assessment

Raja

10.1093/icesjms/fsab248

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35rh Plenary meeting of the Scientific, Technical and Economic Committee for Fisheries (PLEN-10-03)

HAL (Le Centre pour la Communication Scientifique Directe) (2010)

Jordi Abellà Nicholas Bailey Michel Bertignac Casey John Fabienne Daurès

The Scientific, Technical and Economic Committee for Fisheries (STECF) has been established by the European Commission. The STECF is being consulted at regular intervals on matters pertaining to the conservation and management of living aquatic resources, including biological, economic, environmental, social and technical considerations.

Plenary session

10.2788/52748

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Citations (1)

Size-at-maturity of Brown Crab (Cancer pagurus) in Scottish waters based on gonadal and morphometric traits

Fisheries Research (2020)

Carlos Mesquita Helen Dobby Stephanie Sweeting Catherine S. Jones Graham J. Pierce

Allometry

Sexual maturity

10.1016/j.fishres.2020.105610

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Citations (6)

Inferring Feeding Patterns from Stomach Contents Data

Journal of Animal Ecology (1995)

Stephen J. Hall William S. C. Gurney Helen Dobby D.J. Basford Stephen D. Heaney

1. In this paper we show that analysis of changes in the distribution of stomach contents weights over time offers opportunities for improved understanding of fish feeding using data gathered from four of the larger fish species exploiting a sea-loch on the west coast of Scotland. 2. A simple dynamic model of the feeding and digestion process was developed to help understand complex feeding patterns, for which explanatory mechanisms are not immediately obvious. This model characterizes the 24-h cycle in food uptake rate by a small group of parameters whose values are estimated from the data set taken as a whole. 3. As a result of its higher immunity to noisy data, our model has advantages over previous methods for calculating food uptake rates.

Data set

10.2307/5826

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Citations (35)

Report of 2015 ICES Celtic Sea Nephrops Advice Drafting Group (2015 ICES ADGNEPH)

Nathalie A. Steins Colm Lordan Helen Dobby C. Fernández-Llana I. González-Herraiz

Celtic languages

Nephrops norvegicus

Advice (programming)

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