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The assessment of the status of fisheries resources is pivotal due to the importance of marine resources in global food security and to halt the ongoing decline in marine biodiversity. Norway lobster (Nephrops norvegicus) is one of the most valuable resources in the Northeast Atlantic. However, overfishing has caused the decline of several Nephrops stocks over the last decades, particularly in the Nephrops Functional Units (FUs) 25 (NW Spain), 26-27 (NW Spain and North Portugal) and 31 (Cantabrian Sea, North Spain). Since 2003, the information provided by the very low level of landings and fishing effort of these three stocks was insufficient to carry out an adequate analytical assessment, so the base of the assessment has been the trends from commercial catch per unit effort (CPUE). The objective of this study was to carry out the first assessment of these three stocks with an analytical MSY-based model. A review of the available data was made and the stochastic Surplus Production Model in Continuous Time (SPiCT) was fitted for each FU. The results indicate an extremely low biomass for FUs 25 and 26-27 since the mid-nineties well below the reference points. For FU 31, on the other hand, estimated biomass is larger. Our findings also identified long-term temporal and spatial changes in the population dynamic of Nephrops in the Northwest Iberian coast. The results were compare with those obtained in the same stocks with other data-limited methods. Also the role of abiotic factors on the observed dynamic of the stocks was explored. The results of this study are not only relevant for the sustainable exploitation of Norway lobster stocks off the Northwest Iberian coast but provide valuable insights into the suitability and limitations of production models for the assessment of crustacean stocks in general.

The assessment of the status of fisheries resources is pivotal due to the importance of marine resources in global food security and to halt the ongoing decline in marine biodiversity. Norway lobster (Nephrops norvegicus) is one of the most valuable resources in the Northeast Atlantic. However, overfishing has caused the decline of several Nephrops stocks over the last decades, particularly in the Nephrops Functional Units (FUs) 25 (NW Spain), 26-27 (NW Spain and North Portugal) and 31 (Cantabrian Sea, North Spain). Since 2003, the information provided by the very low level of landings and fishing effort of these three stocks was insufficient to carry out an adequate analytical assessment, so the base of the assessment has been the trends from commercial catch per unit effort (CPUE). The objective of this study was to carry out the first assessment of these three stocks with an analytical MSY-based model. A review of the available data was made and the stochastic Surplus Production Model in Continuous Time (SPiCT) was fitted for each FU. The results indicate an extremely low biomass for FUs 25 and 26-27 since the mid-nineties well below the reference points. For FU 31, on the other hand, estimated biomass is larger. Our findings also identified long-term temporal and spatial changes in the population dynamic of Nephrops in the Northwest Iberian coast. The results were compare with those obtained in the same stocks with other data-limited methods. Also the role of abiotic factors on the observed dynamic of the stocks was explored. The results of this study are not only relevant for the sustainable exploitation of Norway lobster stocks off the Northwest Iberian coast but provide valuable insights into the suitability and limitations of production models for the assessment of crustacean stocks in general.

Length-based methods have been widely applied to estimate biological parameters and understand the dynamics of marine resource populations within data-limited stocks. However, to date few studies have tested the sensitivity of parameters in length-based methods examining stocks with different traits and fishery contexts. In the Bay of Biscay and the Iberian Coast ecoregion, SE Europe (International Council for the Exploration of the Sea - ICES, Divisions 8 and 9a), many commercial resources are considered data-limited, and either little is known about their fisheries stock statuses or gaps remain in currently available assessments. Therefore, this study focuses on two of the most used length-based methods, which ICES considers to be the most appropriate to evaluate data-limited stocks, namely length-based indicators (LBI) and the length-based spawning potential ratio (LBSPR). Both methods have been applied to assess the stock statuses of various relevant species in the study area, such as: the small-spotted catshark (Scyliorhinus canicula), European anchovy (Engraulis encrasicolus), blackspot seabream (Pagellus bogaraveo), pouting (Trisopterus luscus), pollack (Pollachius pollachius), and Norway lobster (Nephrops norvegicus). For each stock, model results were compared with available knowledge on their current status. Furthermore, this paper discusses whether unexpected results are related to violations of the main model assumptions (constant total mortality and recruitment, and logistic selectivity) or to a lack of representativeness of stock length composition. A sensitivity analysis was conducted on the two most important input parameters: L∞ (von Bertalanffy asymptotic average maximum body size) and M/k (ratio of natural mortality to von Bertalanffy growth rate). This analysis concluded that the variation/misspecification of both parameters (M/k and L∞) had a considerable impact on the results given by both methods, and that this effect is more significant in th

Length-based methods have been widely applied to estimate biological parameters and understand the dynamics of marine resource populations within data-limited stocks. However, to date few studies have tested the sensitivity of parameters in length-based methods examining stocks with different traits and fishery contexts. In the Bay of Biscay and the Iberian Coast ecoregion, SE Europe (International Council for the Exploration of the Sea - ICES, Divisions 8 and 9a), many commercial resources are considered data-limited, and either little is known about their fisheries stock statuses or gaps remain in currently available assessments. Therefore, this study focuses on two of the most used length-based methods, which ICES considers to be the most appropriate to evaluate data-limited stocks, namely length-based indicators (LBI) and the length-based spawning potential ratio (LBSPR). Both methods have been applied to assess the stock statuses of various relevant species in the study area, such as: the small-spotted catshark (Scyliorhinus canicula), European anchovy (Engraulis encrasicolus), blackspot seabream (Pagellus bogaraveo), pouting (Trisopterus luscus), pollack (Pollachius pollachius), and Norway lobster (Nephrops norvegicus). For each stock, model results were compared with available knowledge on their current status. Furthermore, this paper discusses whether unexpected results are related to violations of the main model assumptions (constant total mortality and recruitment, and logistic selectivity) or to a lack of representativeness of stock length composition. A sensitivity analysis was conducted on the two most important input parameters: L∞ (von Bertalanffy asymptotic average maximum body size) and M/k (ratio of natural mortality to von Bertalanffy growth rate). This analysis concluded that the variation/misspecification of both parameters (M/k and L∞) had a considerable impact on the results given by both methods, and that this effect is more significant in th

The Benchmark Workshop on the application of SPiCT to produce MSY advice for selected stocks (WKMSYSPiCT) is a unique benchmark in that it is ICES first effort to provide MSY advice for category 3 stocks and it incorporated model learning sessions, with model developers and stock assessors, carried out prior to the data evaluation meeting. Thirteen stocks, including nine de-mersal fish stocks and four Functional Units of Nephrops (Nephrops norvegicus), pertaining to four ICES Assessment Working Groups (WGNSSK, WGDEEP, WGCSE and WGBIE), were selected based on the availability of appropriate data and network capacity. Stock assessments using the Surplus Production in Continuous Time (SPiCT) were successful for two demersal stocks, Me-grim (Lepidorhombus spp.) in Division 6.b (lez.27.6b) and Black-bellied anglerfish (Lophius bude-gassa) in divisions 8.c and 9.a (ank.27.8c9a) and for three Functional Units of Nephrops, Norway lobster FU 25 (nep.fu.25), Norway lobster FU 26–27 (nep.fu.2627) and Norway lobster FU 31 (nep.fu.31). WKMSYSPiCT considered that the stocks´ current category could be upgraded since the methodology is appropriate to determine stock status and a short-term catch forecast. Several model configurations were applied for the two Tusk (Brosme brosme) stocks, Tusk in subareas 1 and 2 (usk.27.1-2) and Tusk in subareas 4 and 7-9, and in divisions 3.a, 5.b, 6.a, and 12.b (usk.27.3a45b6a7-912b) and for Norway lobster FU 28–29 (nep.fu.2829), but the available data did not allow to distinguish between two very different stock status. For Pollock (Pollachius pol-lachius) in Subarea 8 and Division 9.a (pol.27.89a), no model configuration passed diagnostics tests. The extensive exploration of input data and model configurations carried out during the workshop resulted in several recommendations regarding the use of historical catches, the stand-ardization of CPUE, including approaches accounting for spatial, target and technological creep effects and, SPiCT model

Length-based methods have been widely applied to estimate biological parameters and to understand the dynamics of marine resource populations within the category of data-limited stocks

Length-based methods have been widely applied to estimate biological parameters and to understand the dynamics of marine resource populations within the category of data-limited stocks. However, few studies have been performed to date to test the parameter sensitivity of length-based methods on stocks with different traits and fishery contexts. In the Bay of Biscay and the Iberian Coast ecoregion, SE Europe (ICES, International Council for the Exploration of the Sea, Divisions 8 and 9a), many commercial resources are considered data-limited and little is known about their stock status or some issues in their current assessment remain open. Therefore, this study focuses on two of the most used length-based methods suggested by ICES as the most appropriate to evaluate data-limited stocks, namely length-based indicators (LBI) and length-based spawning potential ratio (LBSPR). Both methods have been applied to assess the stock status of a number of relevant species in the study area, such as: the small-spotted catshark (Scyliorhinus canicula), European anchovy (Engraulis encrasicolus), blackspot seabream (Pagellus bogaraveo), pouting (Trisopterus luscus), pollack (Pollachius pollachius) and Norway lobster (Nephrops norvegicus). For each stock, model results have been compared with available knowledge of their current status. Furthermore, we discuss if unexpected results can be related to violations of the main model assumptions (constant total mortality and recruitment, and logistic selectivity) or to the non-representativeness of stock length composition. In addition, a sensitivity analysis has been conducted of the two most important input parameters: L∞ (von Bertalanffy asymptotic average maximum body size) and M/k (ratio of natural mortality to von Bertalanffy growth rate). This analysis concludes that the variation/misspecification of both parameters (M/k and L∞) has a considerable impact on the results given by both methods, and that this effect is more significan

Length-based methods have been widely applied to estimate biological parameters and to under-stand the dynamics of marine resource populations within the category of data-limited stocks

Commission Decision of 25 February 2016 setting up a Scientific, Technical and Economic Committee for Fisheries, C(2016) 1084, OJ C 74, 26.2.2016, p. 4–10. The Commission may consult the group on any matter relating to marine and fisheries biology, fishing gear technology, fisheries economics, fisheries governance, ecosystem effects of fisheries, aquaculture or similar disciplines. The STECF reviewed the report of the EWG on Fisheries-dependent Information during its winter 2020 virtual plenary meeting.

Sustainable harvesting of marine populations is achieved through management that relies on assessment of their exploitation and population status. However, most of fish stocks worldwide lack adequate data to assess their status using conventional methods of stock assessment. In addition, the growing requirements to set scientifically based catch limits in several countries, and growing consumer demand for sustainable managed fish have spurred an emerging field of methods for estimating Maximun Sustainable Yield proxies, overfishing thresholds and setting catch limits for stocks with limited data. Building confidence in data-limited assessment methods require evaluation using simulation studies and validation using real data. Within this context, we have selected 3 different data-limited methods, which are supported by the International Council for the Exploration of the Sea's (ICES) for the evaluation of data-limited stocks in the Atlantic waters such as: (1) the stochastic surplus production model in continuous time (SPiCT), (2) the length-based spawning potential ratio (LB-SPR) and (3) the length-based indicators (LBI). We have applied these three methods to a set of different species in a data-poor situation in the Spanish Atlantic waters. In particular we selected species that have different biology and traits as well as fishery pressure to test the goodness of fit of these models. Species selected were the pollack (Pollachius pollachius), small-spotted catshark (Scyliorhinus canicula), common octopus (Octopus vulgaris), southern shortfin squid (Illex coindetii), norway lobster (Nephrops norvegicus) and blackspot seabream (Pagellus bogaraveo). Comparison and evaluation of the performance of these models is presented as well as advantages and limitations. We argue that having models with different assumptions implemented on species with different life histories provide a useful overview of the proposed methods as well as on the status of the selected stocks