Low recruitment 3M Cod Operating Model.

This paper presents the results of F = 0 and the slope and target Harvest Control Rules (HCRs) for a selection of Operating Models (OMs) of 3M Cod with the Low Recruitment regime. The results of these scenarios show that if the current low level of recruitment continues for 2 or 3 more years, the risk of the SSB falling below Blim in the short to medium term is greater than 50% in all scenarios, including those with F=0. Another conclusion that can be drawn from these results is that the current target HCR needs to be improved by investigating more deeply the values of the different parameters of this HCR

A multi-stock harvest control rule based on "pretty good yield" ranges to support mixed-fisheries management

Advice for commercially exploited fish stocks is usually given on a stock-by-stock basis. In light of the ecosystem-based fisheries management, the need to move towards a holistic approach has been largely acknowledged. In addition, the discard bans in some countries requires consistent catch advice among stocks to mitigate choke species limiting fisheries activity. In this context, in 2015, the European Commission proposed the use of fishing mortality ranges around fishing mortality targets to give flexibility to the catch advice system and improve the use of fishing opportunities in mixed-fisheries. We present a multi-stock harvest control rule (HCR) that uses single stock assessment results and fishing mortality ranges to generate a consistent catch advice among stocks. We tested the performance of the HCR in two different case studies. An artificial case study with three stocks exploited simultaneously by a single fleet and the demersal mixed-fishery operating in Bay of Biscay and Celtic Sea. The HCR produced consistent catch advice among stocks when there was only a single fleet exploiting them. Even more, the HCR removed the impact of the discard ban. However, in a multi-fleet framework the performance of the HCR varied depending on the characteristics of the fleets

Size dependent predation in piscivorous larval stages of three tuna species

The bluefin tuna (Thunnus thynnus) is a heavily fished temperate tuna that spawns in the Mediterranean Sea; the area off the Balearic Islands is a key spawning area. Other abundant tunas, including albacore (Thunnus alalunga) and the small bullet tuna (Auxis rochei) spawn in the same area. The three species temporally overlap during the summer spawning period of the adults. Because they are clearly piscivorous already at very early larval stages, we expect strong interactions both in terms of a direct predator–prey relationship and as competitors for food resources. In this study, we focus on understanding the size dependent trophic interactions among the three species at the different developmental larval stages. First, we describe the environmental and biological scenarios where different size stages of the three species co-occur through the application of generalized additive model (GAM) analyses to field data collected during cruise surveys in 2004–2005. We then develop an individual_based model (IBM) to evaluate inter- and intraspecific predation rates considering size structured prey and predator fields in the framework of piscivorous behaviour. The results demonstrate how predation mortality rates influence the spawning location of the three speci

Results of the 3M Cod MSE

The general objective of the 3M Cod MSE is to maintain the SSB of this species in the safe zone as defined by the NAFO precautionary approach framework and to assure the optimum utilization, rational management and conservation of the 3M cod stock. Based on this, five performance objectives were tested via five different Performance Statistics. Six different OMs and two HCRs with three different Ftarget were tested. The six OMs come from different assumptions over M and over the Stock-Recruitment relationship (SRR). The two HCRs are one model-based (based on the Bayesian XSA model approved by SC) and one model-free (based on the EU-FC survey). A 20% constraint of annual variation of TAC was set for both HCR. Based on this, a total of 24 scenarios were tested and results projected for the period 2014-2025. Differences in the results come mainly from the assumed stock recruitment relationship and in a much lesser extent of assumed M and the different Ftarget levels tested. The SSB have an increasing trend in all cases reaching a level well above Blim at the end of the projected period. There are two main trends in yields, one for the scenarios with the model-based HCR and other for the scenarios with the model-free HCR. In the first case, landings decrease to 6 500 tons in 2020, and after that increase until 2025 reaching a value between 10 500 and 15 000 tons, depending on the SRR assumed. In the case of the model-free HCR, until 2023 the decrease is very small and then a quiet constant value between 5 000 and 11 000 tons is reached. None of the tested HCR reached the established performance objectives in the 2016-2023 period but most of the scenarios met the performance objectives after 2024. The main reasons for not achieving these objectives are the high initial F and catch levels and the 20% catch constraint. The necessary period to achieve the performance objectives would be longer if we had applied a more restrictive TAC constraint (15% or 10%). If the TAC constraint is not applied, lower landings are allowed in the short-term period (2016-2020), but after that the increase in TAC is higher than if the constraint is applied

A NOVEL INDEX OF ABUNDANCE OF JUVENILE YELLOWFIN TUNA IN THE ATLANTIC OCEAN DERIVED FROM ECHOSOUNDER BUOYS

The collaboration with the Spanish vessel-owners associations and the buoy-providers companies, has made it possible the recovery of the information recorded by the satellite linked GPS tracking echosounder buoys used by the Spanish tropical tuna purse seiners and associated fleet in the Atlantic since 2010. These instrumental buoys inform fishers remotely in real-time about the accurate geolocation of the FAD and the presence and abundance of fish aggregations underneath them. Apart from its unquestionable impact in the conception of a reliable CPUE index from the tropical purse seine tuna fisheries fishing on FADs, echosounder buoys have also the potential of being a privileged observation platform to evaluate abundances of tunas and accompanying species using catch-independent data. Current echosounder buoys provide a single acoustic value without discriminating species or size composition of the fish underneath the FAD. Therefore, it has been necessary to combine the echosounder buoys data with fishery data, species composition and average size, to obtain a specific indicator. This paper presents a novel index of abundance of juvenile yellowfin tuna in the Atlantic Ocean derived from echosounder buoys for the period 2010-2018

Bioeconomic Modelling Applied to Fisheries with R/FLR/FLBEIA

The main objectives of the study presented in this report were to test the FLBEIA API, condition an operating model for the North Sea mixed fisheries and provide feedback on bioeconomic modelling limitations. Additionally, Fishrent and Fcube were also tested. FLR, FLBEIA, Fishrent and Fcube are software packages implemented by the scientific community studying fisheries to run bioeconomic models. A large test was carried out on FLBEIA by both running existing examples and trying to implement a bioeconomic model for the North Sea. In general the group felt FLBEIA is on the correct path to provide a bioeconomic modeling framework, although some work is still required. FLBEIA is not ready yet for production. A list of bugs and improvements was assembled. Conditioning a bioeconomic operating model for the North Sea showed the difficulties of merging economic and biological information. Inconsistencies on the effort definition seem to create additional problems when relating both sources of information. This subject must be further explored. The exercise was successful but data problems prevented the performance of a full economic analysis, although trend analysis on economic indicators for each scenario tested was possible. Nevertheless, these results must be taken carefully.JRC.G.4-Maritime affair

Potential Operating Models, Harvest Control Rules and Performance Statistics for the NAFO 3M Cod MSE.

This document presents a proposal of possible Operating Models (OMs), Harvest Control Rules (HCR) and Performance Statistics (PS) to carry out the Management Strategies Evaluation (MSE) for the 3M cod of NAFO. This proposal will have to be reviewed by the NAFO SC to decide the first set of OMs to test with the possible HCRs in the 3M Cod MSE