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Introduction
My research has focused on stress and mortality among animals encountering and being released from fishing gear, including quantifying “unaccounted” fishing mortality. Recently, I have been developing a strategy with colleagues to introduce welfare responsible practices to commercial fisheries, with the aim of making fisheries more ethically responsible and sustainable by reducing unwanted catches & collateral mortality, improving meat quality & product shelf-life.
Publications
Publications (110)
The release of unwanted catches (UWC) from purse seines, while the catch is still in the water, is known as “slipping”. Once thought to be a benign process, compared to discarding UWC overboard from the fishing vessel, it is now recognised that “slipping” can lead to significant mortality in the released fish if done inappropriately. In this chapte...
The introduction of catch welfare to commercial wild-capture fisheries will be challenging. In this chapter, we discuss how taking a science-based approach to understanding catch welfare in commercial fisheries could lead to practical solutions to improving welfare that will not only have ethical benefits, but may also have tangible benefits for th...
On the 1st of January 2014, the European Union introduced a phased discard ban or “Landing Obligation” for regulated species, as part of Common Fisheries Policy (CFP) Basic Regulation (Article 15). Today, in the post-Landing Obligation world, it may appear that a report on discard survival has little relevance. However, The Landing Obligation polic...
Crowded (stressed) and unstressed Atlantic mackerel with or without pre-freezing holding in refrigerated sea water (RSW) were stored at -19°C for ∼12 months and analysed for nucleotide degradation (K value), muscle pH, water holding capacity (WHC), fillet firmness, cathepsin B/L like activity, lipid oxidation and fillet colour. The frozen storage s...
The impacts of wild capture fishing on animal welfare are poorly understood. During purse seine fishing for Atlantic mackerel (Scomber scrombrus), catches are crowded to high densities to facilitate pumping onboard. This study aimed to monitor fish welfare during crowding events in the Norwegian purse seine fishery, and to identify relevant drivers...
The Norwegian quota for Atlantic bluefin tuna (ABT) (Thunnus thynnus) is not completely caught every year. This is paradoxical because Norway is a leading fishing nation. The fishery is currently executed by rod-and-reel and purse seine, with ∼ 80 % of the quota being allocated to the latter. Purse seine is therefore the main determinant for the ov...
Evaluating artificial light as a bycatch reduction device (bycatch reduction light, “BRL”) requires a multidisciplinary approach that applies knowledge of fisheries science, fishing technology, engineering, physics, optics, vision biology, oceanography, animal behavior, economics, and social science. To support the continued evaluation of BRL, thes...
From 2020 to 2022, a number of experiments were carried out in the Skagerrak investigating trawl selection and survival of deep-water prawn (Pandalus borealis). The main objective was to quantify what proportion of the total selection occurs at the sea surface and to investigate associated post-escape survival rates. The survival of escapees likely...
Stock assessments routinely evaluate the status of commercially harvested species, but seldom account for the possible mortality of released or escaping fish. This study presents a method for estimating the escape survival of the red mullet (Mullus barbatus) from demersal trawling in the Central Mediterranean Sea. Fish escaping from the trawl coden...
Blue whiting (Micromesistius poutassou) is harvested in the Northeast Atlantic by a multinational fleet of pelagic trawlers. Occasionally, vessels take catches which exceed their remaining holding capacity and in extreme cases large catches cause codends to burst, resulting in spill of catch. To control catch quantity, a catch limitation system was...
Wild capture can be stressful for fish. Stress has the potential to induce mortality in released unwanted catches or negative flesh quality consequences in retained ones. Such effects compromise sustainable natural resource management and industry profitability. Mitigating stress during capture is therefore desirable. Biological indicators of stres...
Understanding how animals physiologically respond to capture and release from wild capture fishing is fundamental for developing practices that enhance their welfare and survival. As part of purse seine fishing for small pelagic fish in northern European waters, excess and/or unwanted catches are routinely released from the net in a process called...
The landing obligation in the revised European Union Common Fisheries Policy allows for exemptions to obligatory landing of the entire catch for species for which “high survival” of discards can be demonstrated. Nephrops norvegicus is an important target species in many fisheries across Europe in the Mediterranean Sea, NE Atlantic Ocean and North S...
Capture-based aquaculture (CBA) combines aquaculture practices with capture fisheries to keep the catch alive for either short or long periods of time, for feeding or for live storage. CBA enables us to market numerous species ranging from molluscs, scallops and crustaceans to fish such as tuna, cod, eel and groupers. In CBA, handling and adaptatio...
In commercial wild capture pelagic fisheries it is common practice to crowd catches to high densities to allow efficient pumping onboard. Crowding during the final stages of purse seine capture for small pelagic species often results in intense and sustained behavioural escape responses. Such a response may trigger a shift in energy production from...
Inducing unconsciousness in fish using electrical stunning prior to slaughter may improve fish welfare and fillet quality if such practises can be disseminated into wild capture fisheries. The objectives of this study were to: 1) evaluate if an established slaughter protocol consisting of dry electrical stunning (using a coupled AC/DC current at ≈...
Stress to fish during harvest in wild capture fisheries is known to negatively influence subsequent survival in catches that are released. Therefore, if fisheries are to be conducted sustainably, there is a need to promote good fish welfare during the capture process. Purse seine fishing is a widespread and efficient fishing method. However, captur...
Stereocamera system setup.
Detail of the stereo-camera system, calibration and deployment strategy.
(DOCX)
Measurement of the tail beat amplitude, nearest neighbour distance and nearest neighbour angular deviation behavioural metrics.
Detail of how cartesian coordinates were used to determine nearest neighbour distances and angular deviations and how tail beat amplitude was quantified.
(DOCX)
Statistical analysis procedures.
Statistical analysis details for the tail beat amplitude, nearest neighbour distance and nearest neighbour angular deviation behavioural metrics.
(DOCX)
Tail beat frequency modelling results for all monitoring periods.
Linear mixed model coefficients for the relationship between tail beat frequency and monitoring periods (included in the model as “Monitoring code”), the stressors treatments (“Crowded”, “Hypoxia” and their interaction) and experimental phase (“Phase”).
(DOCX)
Nearest neighbour angular deviation in pitch (ADP) dataset.
(CSV)
Tail beat frequency (TBF) dataset.
(CSV)
Tail beat amplitude (TBA) dataset.
(CSV)
Nearest neighbour distance (NND) dataset.
(CSV)
Nearest neighbour angular deviation in yaw (ADY) dataset.
(CSV)
Randomly selected examples of the perspective given by the vertically orientated GoPro camera.
Containing examples of both crowding and non-crowding treatments.
(MP4)
Tail beat frequency responses throughout all monitoring periods.
Model predicted mean (± 95% confidence intervals) tail beat frequency across all monitoring periods for different stressor treatments in the three experimental phases. The red shaded area indicates the monitoring periods corresponding to the application of the stressor. The underlying...
Tail beat amplitude, nearest neighbour distance and nearest neighbour angular deviation results.
Detail and visualisation of tail beat amplitude, nearest neighbour distance and nearest neighbour angular deviation results, including description of methodological issues encountered during stereo-camera observation of behaviour during “crowding” and “...
The release of unwanted fish from purse seines whilst still in the water is termed slipping and may lead to significant mortality following release. The objective of this study was to determine the fish welfare implications of a new slipping methodology in which fish are released via a discharge opening formed in the bunt end of the purse seine net...
“Single fish” video sequence.
Examples of the “Single fish” behavioural unit, recorded by the vertically orientated discharge camera.
(MP4)
“No escape” video sequence.
An example of the “No escape” behavioural unit, recorded by the horizontally orientated discharge camera.
(MP4)
“Return” video sequence.
Examples of the “Return” behavioural unit, with persectives recorded by the both the vertically orientated and the horizontally orientated discharge cameras (equipped with red light).
(MP4)
“Dataset B”.
Dataset of behavioural time budgets per slipping event.
(CSV)
“Orderly” video sequence.
Examples of the “Orderly” behavioural unit, with persepctives recorded by the both the horizontally orientated and the vertically orientated discharge cameras.
(MP4)
“Disorderly” video sequence.
Examples of the “Disorderly” behavioural unit, recorded by the horizontally orientated discharge camera.
(MP4)
“Dataset A”.
Dataset containing observations of tail beat frequency during and after escape from purse seines.
(CSV)
“Dataset C”.
Dataset of the most dominant slipping behaviour per 10 second interval of slipping.
(CSV)
The most dominant slipping behaviour patterns over time for mackerel and herring from two different vessels.
Vertical bar represent 10 second bins. A: Mackerel from Vessel A; B: Mackerel from Vessel B; C: Herring from Vessel A; D: Mackerel from Vessel B.
(TIF)
“Small group” video sequence.
An example of the “Small group” behavioural unit, recorded by the horizontally orientated discharge camera.
(MP4)
“Drop camera” video sequence.
Examples of the perspective given by the drop camera.
(MP4)
This chapter describes the process and evaluation behind several of the flexibility elements introduced into the Basic Regulation. Firstly, it describes how a fishery may be granted a “high survival exemption” (HSE) or “de minimis” to the Landing Obligation, for a particular regulated species. It details the process of generating any exemption supp...
In many countries, policies regarding reduction of unwanted catch and discards are crafted in response to concerns regarding accountability, conservation, and waste as well as scientific needs to fully account for all sources of fishing mortality. It is important to note, however, that unwanted catch is minimal and most, or all, of the catch has va...
Bottom trawling for crustaceans in Portuguese coastal waters is an important fishery in terms of revenue, despite its negative impacts on deep-sea ecosystems. This fishery catches large amounts of unwanted species that were discarded for various reasons before the introduction of the Landing Obligation, which banned the discarding of regulated spec...
Artificial light in baited pots substantially increases the catch of cod (Gadus morhua) by attracting active bait, krill (Thysanoessa inermis). The use of pots in the north Atlantic finfish fisheries is negligible because this fishing method typically has a low capture efficiency. Large numbers of individuals encounter baited pots, but the proporti...
The effects of two different slipping methods on the survival, physical and physiological response of sardines, Sardina pilchardus, captured in a purse-seine fishery were investigated in southern Portugal. Sardines were collected and transferred into holding tanks onboard a commercial fishing vessel after being captured, crowded and deliberately re...
Survival estimates for sardine using Kaplan-Meier survival curves (dashed line), overlaid with the predictions from the selected mixture-distribution survival model M3 (solid lines with 95% confidence bands) for the three treatment replicates (1–3): Control, standard slipping (SS) and modified slipping (MS).
(TIF)
In the Balearic Islands, different trammel net designs have been adopted to promote fisheries sustainability and reduce discards. Here, we compare the catch performance of three trammel net designs targeting the spiny lobster Palinurus elephas in terms of biomass, species composition and revenue from commercial catches and
discards. Designs differ...
Data of commercial species caught by trammel nets of different gear material.
Supplementary information.
Data of trammel net deployment date and location and as well as other associated information.
Non-commercial invertebrate fraction of the catch by trammel nets.
Most fishes and crustaceans respond to light, and artificial light sources may therefore be an efficient stimulus to manipulate behaviours in aquatic animals. It has been hypothesised that the catch efficiency of pots could be increased if prey, for example krill, can be attracted into the pots providing a visual stimulus and a source of live bait....
Effect of flickering light and wavelengths on krill.
(DOCX)
Overview of conducted experiment.
Number of replicates within the different light treatment combination, for the krill and cod experiment.
(DOCX)
The selectivity of fishing gears with respect to fish species and size is important, both for fisheries management and fishing operations. Purse seining is an efficient, environmentally friendly fish capture methodology generally targeting single species aggregations, but once a fish school has been selected and surrounded by the seine, there is no...
The fish mortalities during the experiment.
(PDF)
Randomly chosen video sequence among responses scored as 3.
(MP4)
R script to read the supporting data set for regenerating the tests and figures in the paper.
(R)
The swimming speed as a function of time.
(TIF)
Randomly chosen video sequence among responses scored as 0.
(MP4)
Randomly chosen video sequence among responses scored as 1.
(MP4)
Randomly chosen video sequence among responses scored as 2.
(MP4)
Contains data to re-generate the tests and the figures in the paper.
(CSV)
Wild haddock (Melanogrammus aeglefinus) of commercial size (0.8–2.49 kg, 45–60 cm) were swum to exhaustion in a large swim tunnel and then allowed to recuperate for 0, 3 or 6 h, to investigate the effects of exhaustive swimming on blood glucose, blood lactate and post mortem development of fillet quality. There was a positive linear relationship be...
D2-15-Guidance-on-Promoting-Survival-of-Discarded-Fish
In capture-based aquaculture (CBA) wild cod (Gadus morhua) are caught and held in sea cages in order to supply fresh, high-quality fish throughout the year. CBA of cod is attracting growing interest among the Norwegian fishing industry. The most common gear for CBA is the demersal seine net (Danish or Scottish seine). However, there are powerful in...
This study assesses the seabed pressure of towed fishing gears and models the physical impact (area and depth of seabed penetration) from trip-based information of vessel size, gear type, and catch. Traditionally fishing pressures are calculated top-down by making use of large-scale statistics such as logbook data. Here, we take a different approac...