The current fish stock assessment process in Europe can be very resource- and time-intensive. The scientists involved require a very particular set of skills, acquired over their career, drawing from biology, ecology, statistics, mathematical modelling, oceanography, fishery policy, and computing. There is a particular focus on producing a single “best” stock assessment model...
Biomass, catchability, and natural mortality are key parameters in fish stock assessment. Yet, it is difficult to estimate these quantities, especially natural mortality, when only fishery data are available. Using a method of population depletion analysis, we estimated these population and biological quantities for the white banana prawn (Penaeus merguiensis) in Australia's...
Cohort slicing can be used to obtain catch-at-age data from length frequency distributions when directly measured age data are unavailable. The procedure systematically underestimates the relative abundance of the youngest age groups and overestimates abundance at older ages. Cohort-sliced catch-at-age data can be used to estimate total mortality rate (Z) using a regression...
Management of marine resources depends on the assessment of stock status in relation to established reference points. However, many factors contribute to uncertainty in stock assessment outcomes, including data type and availability, life history, and exploitation history. A simulation–estimation framework was used to examine the level of bias and accuracy in assessment model...
The World Conference on Stock Assessment Methods (July 2013) included a workshop on testing assessment methods through simulations. The exercise was made up of two steps applied to datasets from 14 representative fish stocks from around the world. Step 1 involved applying stock assessments to datasets with varying degrees of effort dedicated to optimizing fit. Step 2 was applied...
Interpretation of data used in fisheries assessment and management requires knowledge of population (e.g. growth, natural mortality, and recruitment), fisheries (e.g. selectivity), and sampling processes. Without this knowledge, assumptions need to be made, either implicitly or explicitly based on the methods used. Incorrect assumptions can have a substantial impact on stock...
This special volume of the ICES Journal compiles contributions from the World Conference on Stock Assessment Methods for Sustainable Fisheries (July 2013, Boston, USA). The conference was the product of a strategic initiative on stock assessment methods that engaged many national and regional fishery management organizations to assure that scientists can apply the most...
Different marine and coastal activities have diverse economic, environmental, and socio-cultural objectives, which can lead to conflict when these multidimensional activities coincide spatially or temporally. This is sometimes driven by a lack of understanding or other users' needs and consequentially adequate planning and the utilization of a common language is essential. By...
The increased mesh resistance to opening of netting panels manufactured with thick and stiff twines has a notable impact in the structural response and selective performance of the fishing gears. The only available method to quantify the mesh resistance to opening of netting panels was described in Sala et al. (in Experimental method for quantifying resistance to the opening of...
Based on size selectivity data for more than 25 000 cod (Gadus morhua) collected during experimental trawl fishing with six different codends, all of which included a square mesh panel, we investigated the effect on cod-release efficiency based on the size of the square mesh panel area, position of the square mesh panel, and stimulation of the escape response. Based on the...
To improve assessments of the environmental risks of aquaculture, a series of simulated escapes of farmed Atlantic salmon (Salmo salar L.) from seawater netpens were performed. Individually tagged post-smolts and adult Atlantic salmon were released from various locations at different times of the year. Post-smolts that escaped during their first summer were capable of rapid...
Certain facets of the population dynamics of a species are hard to quantify, including stock structure. In particular, geographical boundaries of stocks or populations are often hard to estimate. This document discusses the application of a recent tagging method, applicable when breeding populations overlap on feeding grounds. The tagging efficiency is augmented with information...
The red king crab (Paralithodes camtschaticus) is native to the Bering Sea, but was deliberately introduced to the Barents Sea during the 1960s. Since then, the red king crab has spread to Norwegian waters, and crab densities have increased sufficiently to support a coastal fishery. Information about total and natural mortality, which is important to ensure adequate management...
The ling, Molva molva, is a commercially exploited demersal gadid fish distributed throughout the Northeast Atlantic. Here, we provide the first study of population genetic structure by genotyping 6 geographically distinct samples with 11 microsatellite DNA markers. The results rejected the hypothesis of a single ling stock in the Northeast Atlantic, and rather suggested the...
We used carbon and oxygen isotope ratios (δ13C and δ18O) in otoliths as a tool for identifying the nursery origin of Atlantic bluefin tuna (Thunnus thynnus) caught in the eastern North Atlantic Ocean (Bay of Biscay). Juvenile and adult bluefin tuna were collected over three consecutive years (2009—2011) using the regional bait boat fleet. Otolith δ13C and δ18O values of bluefin...
A molecular approach was successfully developed to discriminate between spawned eggs of the pelagic carangids Trachurus declivis and Trachurus novaezelandiae collected during ichthyoplankton surveys conducted in October 2002 and 2003 along shelf waters of Queensland (Qld) and New South Wales (NSW), in southeastern Australia (25o50′–37o30′S). Visually identified Trachurus eggs...
Benthos plays a significant role as substrate, refuge from predation and food for a wide variety of fish and invertebrates of all life stages and should therefore be considered in the ecosystem approach (EA) to management. Epibenthos from trawl catches, used in annual assessments of commercial fish stocks, was identified and measured on-board. The 2011 dataset present the...
Marine protected areas (MPAs) are increasingly used to address multiple marine management needs, and the incorporation of stakeholders into the MPA planning and designation processes is considered vital for success. Commercial fishers are often the stakeholder group most directly affected by spatial restrictions associated with MPAs, and the success of MPAs often depends, at...
The aim is to determine the environmental requirements, estimate the extent of suitable habitat for three sea pen species, and assess the implications for marine protected areas (MPAs). The sea pen Funiculina quadrangularis and the habitat associated with two further sea pen species, Virgularia mirabilis and Pennatula phosphorea, are of key conservation importance and are...
Knowledge of swimming depths and migration routes of homing Atlantic salmon in open coastal zones is urgently required to inform decisions on managing the species, e.g. for the sustainable development of marine renewable energy. In May–June 2013, pop-up satellite tags programmed to detach from fish after 1–10 d were fitted to 50 adult salmon on the northern coast of Scotland...
For conservation purposes, it is important to evaluate potential population consequences of noise disturbance. Based on maximum reported sound levels of no response to sonar, a mathematical model is used to predict the potential risk to the population of herring (Clupea harengus) when these levels are exceeded. Results show that risk varies with season depending on density of...
Shallow, subtidal waters of coastal embayments are the primary nursery habitats of juvenile Pacific cod through much of their range. However, the importance of these habitats to the Bering Sea population is poorly understood as the Bering Sea offers relatively little of this habitat. In this study, we examined the use of demersal and pelagic habitats in the southeast Bering Sea...
The proportion of mature fish at age or length is one of the most important population attributes in assessing reproductive potential. This proportion is usually named the maturity ogive. The most crucial step in estimating this proportion deals with maturity staging assessed by macroscopic or histology analysis. Macroscopic analysis is relatively inexpensive but usually...
Demersal fisheries targeting a few high-value species often catch and discard other “non-target” species. It is difficult to quantify the impact of this incidental mortality when population biomass of a non-target species is unknown. We calculate biomass for 14 demersal fish species in ICES Area VIIg (Celtic Sea) by applying species- and length-based catchability corrections to...
Marine fish populations have high variation in cohort strength, and the production of juveniles (recruitment) may have persistent positive or negative residuals (autocorrelation) after accounting for spawning biomass. Autocorrelated recruitment will occur whenever average recruitment levels change between oceanographic regimes or due to predator release, but may also indicate...