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- Assessing the effects of hook, bait and leader type as potential mitigation measures to reduce bycatch and mortality rates of shortfin mako: a meta-analysis with comparisons for target, bycatch and vulnerable fauna interactionsPublication . Rosa, Daniela; Casaca Santos, Catarina; Coelho, RuiA meta-analysis of 24 publications was conducted to assess effects of hook, bait and leader type on retention rates of target, bycatch and vulnerable species of the pelagic longline fishery. Retention rate and at-haulback mortality rate analyses considered hook type, bait type, the combination of both variables and leader type. Turtles and swordfish had a lower retention rate with circle hooks. In contrast, retention rates of 3 sharks and 2 tuna species were greater with circle hooks. Bait type alone did not seem to significantly influence the retention rates of most of the species examined. Results were mixed when considering the combined effects of hook and bait type. Wire leader led to a decrease in retention rates of bony fishes and a mix for elasmobranchs. For at-haulback mortality, hook type was the most influential, while bait type only influenced blue shark at-haulback mortality. Leader type did not have a significant effect. The results presented here should be considered preliminary. Future work will consider information on at-haulback mortality rates for bony fishes and sea turtle and expanded information on fishery characteristics.
- Characterization and standardization of Atlantic sailfish (Istiophorus albicans) catch rates in the east Atlantic from the Portuguese pelagic longline fisheryPublication . Coelho, Rui; Lino, Pedro; Santos, MiguelThis document analyzes the catch, effort and standardized CPUE trends for the eastern Atlantic stock of Atlantic sailfish (Istiophorus albicans) captured by the Portuguese pelagic longline fleet from 1999-2015. Nominal annual CPUE were calculated as kg/1000 hooks and were standardized with Generalized Linear Models (GLM) with Tweedie distribution and using year, quarter, area and targeting effects (ratios) as explanatory variables. Model goodness-of-fit was determined with AIC and the pseudo coefficient of determination, and model validation was analyzed with residual analysis. The final standardized CPUE series shows a general decrease in the initial years, between 1999 and 2010, followed by a general increase in the more recent years, until 2015, with some inter-annual oscillations. This paper presents the first index of abundance for Atlantic sailfish estimated from captures from the Portuguese pelagic longline fleet in the east Atlantic and can be used for future stock assessments of the species
- Modeling species composition and mortality rates of sea turtles in the Portuguese pelagic longline fishery targeting swordfish in the Atlantic Ocean: preliminary results using statistical modelsPublication . Coelho, Rui; Rosa, Daniela; Lino, Pedro; Santos, Miguel
- New observations on the bluefin tuna trap fishery off southern Portugal (NE Atlantic) between 1998-2014: trends on potential catches, catch-at-size and sex ratiosPublication . Santos, Miguel; Rosa, Daniela; Coelho, Rui; Lino, PedroThis paper updates information previously presented on the bluefin tuna catches from a tuna trap fishery operating off the southern coast of Portugal (Algarve). Trends of intra- and interannual catches were analysed and relationships between the potential catches and ICCAT management regulations for the Mediterranean Sea explored. The catch rates of bluefin tuna in the tuna trap off the Algarve remained relatively low between 1998 and 2008, but were followed by increasingly high catches thereafter, with an observed peak during the 2011 season. Significant negative correlations were observed between the catches and the number of allowable fishing months for purse-seines, longlines and bait boats in the Mediterranean Sea, meaning that the catch increased as the number of allowable fishing months for those fishing gears decreased. On the other hand, a positive relationship was observed between the catches and the minimum landing size (MLS), meaning that the catch rates in the tuna trap increased as the MLS for bluefin tuna also increased. These results seem to corroborate other fisheries indicators regarding the recovery of the Eastern Atlantic and Mediterranean Sea stock.
- Post-release mortality of shortfin mako in the Atlantic using satellite telemetry: preliminary resultsPublication . Domingo, Andrés; Casaca Santos, Catarina; Carlson, John; Natanson, Lisa; Cortés, Enric; Mas, Federico; Miller, Philip; Hazin, Fábio H. V.; Travassos, Paulo; Coelho, RuiThis paper provides an update of the study on post-release mortality of the shortfin mako, Isurus oxyrinchus developed within the ICCAT Shark Research and Data Collection Program (SRDCP). Up to date, 34 tags (14 sPATs and 20 miniPATs) have been deployed by observers on Brazilian, Portuguese, Uruguayan, and US vessels in the temperate NE and NW, Equatorial and SW Atlantic. Data from 28 out of 34 tagged specimens could be used to obtain preliminary information regarding post-release mortality, resulting in a total of 7 mortality and 21 survival events.
- Progress report for SRDCP on the Atlantic-wide study on the age and growth of shortfin mako sharkPublication . Rosa, Daniela; Mas, Federico; Mathers, Alyssa; Natanson, Lisa J.; Domingo, Andrés; Carlson, John; Coelho, RuiThe ICCAT Shark Research and Data Collection Program (SRDCP) aims to develop and coordinate science and science-related activities needed to support provision of sound scientific advice for the conservation and management of pelagic sharks in the Atlantic. This Program was developed in 2013-2014 by the Sharks Species Group, and framed within the 2015-2020 SCRS Strategic Plan. Within this Program, a specific study on the age and growth of shortfin mako in the Atlantic was developed, with the purpose of contributing to the 2017 ICCAT SMA stock assessment. In the paper, we provide an update of the project, including preliminary growth models for the North Atlantic Ocean.
- Standardized CPUE of blue shark in the Portuguese pelagic longline fleet operating in the north AtlanticPublication . Coelho, Rui; Santos, Miguel; Lino, PedroThis working document analyzes the catch, effort and standardized CPUE trends for the north Atlantic blue shark captured by the Portuguese pelagic longline fleet. Nominal annual CPUE were calculated as kg/1000 hooks and were standardized with Generalized Linear Models (GLM) and Generalized Linear Mixed Models (GLMM) using year, quarter, area, gear type, targeting effects and area:quarter interactions as fixed factors, and year:area as random effects. Sensitivity analyzes were carried out for the model type (lognormal, tweedie, gamma or delta lognormal), the definition of targeting effects (based on ratios or cluster analysis), and definition of areas. Model goodness-of-fit and comparison was carried out with AIC and the pseudo coefficient of determination (R2 ), and model validation with a residual analysis. The final standardized CPUE trend shows a general increase over the studied period, between 1997 and 2014, with some inter-annual oscillations. This paper presents the first index of abundance for the blue shark estimated from captures from the Portuguese pelagic longline fleet in the North Atlantic, and can be used in future stock assessments models.
- Updates on habitat use and migrations patterns for shortfin mako in the Atlantic using satellite telemetryPublication . Casaca Santos, Catarina; Domingo, Andrés; Carlson, John; Natanson, Lisa; Travassos, Paulo; Macias, David; Cortés, Enric; Miller, Philip; Hazin, Fábio H. V.; Mas, Federico; Ortiz de Urbina, Josetxu; Coelho, RuiThis paper provides an update of the study on habitat use for shortfin mako, developed within the ICCAT Shark Research and Data Collection Program (SRDCP). A total of 43 tags (29 miniPATs and 14 sPATs) have been deployed by observers on Portuguese, Uruguayan, Brazilian, Spanish and US vessels in the temperate NE and NW, Equatorial and SW Atlantic. Data from 41 tags/specimens are available, and a total of 1656 tracking days have been recorded. Results showed shortfin mako moved in multiple directions, travelling considerable distances. Shortfin mako sharks spent most of their time above the thermocline (0-90 m), between 18 and 22 °C. The main plan for the next phase of the project is to continue the tag deployment during 2019 in several regions of the Atlantic.
- Updates on post-release mortality of shortfin mako in the Atlantic using satellite telemetryPublication . Miller, Philip; Casaca Santos, Catarina; Carlson, John; Natanson, Lisa; Cortés, Enric; Mas, Federico; Hazin, Fábio H. V.; Travassos, Paulo; Macias, David; Ortiz de Urbina, Josetxu; Coelho, Rui; Domingo, AndrésThis paper provides an update of the study on post-release mortality of the shortfin mako, Isurus oxyrinchus developed within the ICCAT Shark Research and Data Collection Program (SRDCP). Up to date, 43 tags (14 sPATs and 29 miniPATs) have been deployed by observers on Brazilian, Portuguese, Spanish, Uruguayan, and US vessels in the temperate NE and NW, Equatorial and SW Atlantic. Data from 35 out of 43 tagged specimens could be used to obtain preliminary information regarding post-release mortality, resulting in a total of 8 mortality and 27 survival events.