[MARMAM] New publications of Ecomega Research Group

Eduardo Secchi edu.secchi at furg.br
Thu Jun 3 17:42:00 PDT 2021

Dear MARMAMers,
We would like to share these two new publications of the Ecology and Conservation of Marine Megafauna (Ecomega) research team.

Prado JHF, Kinas PG, Pennino MG, Seyboth E, Silveira FRG, Ferreira EC & Secchi ER (2021). Definition of no-fishing zones and fishing effort limits to reduce franciscana bycatch to sustainable levels in southern Brazil. Animal Conservation DOI:101111/acv.12679

Abstract: Franciscana Pontoporia blainvillei bycatch has been high for near six decades in western South Atlantic, with large regional variation. In 2012, the Brazilian Government-regulated gillnet fisheries in south and southeast Brazil by reducing fishing effort and establishing no-fishing zones. However, there is evidence that the magnitude of franciscana bycatch remains high and unsustainable. The aims of this study were to identify hotspot areas of franciscana bycatch associated with two main gillnet fisheries and to propose no-fishing zones combined with limited total allowable fishing effort (i.e. total net length per season) in order to meet management objectives in southern Brazil. A hierarchical Bayesian model using integrated nested Laplace approximation (INLA) was employed based on 1427 reported settings from 1999 to 2003 and 2006 to 2009. Hotspot zones were detected and are proposed as no-fishing zone during the white croaker Micropogonias furnieri and striped weakfish Cynoscion guatucupa gillnet fishing seasons. Their extents represent 6% (1466.8 km2) and 19% (4493.7 km2) of the fishing ground (23 204.1 km2) during croaker and weakfish fishing seasons respectively. The total allowable fishing effort estimated outside the no-fishing zones were estimated at 541 km (95% credible interval (CrI) [339; 940]) during croaker and 688 km (CrI [312; 2,166]) during weakfish fishing seasons, one order of magnitude lower than the current total fishing effort. The drastic reduction of total fishing effort estimated in this study is largely due to weak protection measures since the gillnet fisheries became the major conservation concern for franciscana by the end of 1970s in southern Brazil. Although the implementation of the proposed exclusion zones and limiting fishing effort will strongly impact the status quo, they were based on the best scientific evidence and on a clearly defined management goal to reduce the risk of the franciscana population’s collapse in southern Brazil.

Fruet PF, Möller LM & Secchi ER (2021). Dynamics and viability of a small estuarine-resident population of Lahille’s bottlenose dolphins from southern Brazil. Front. Mar. Sci. https://doi.org/103389/fmars.2020.593474 <https://doi.org/103389/fmars.2020.593474>

Abstract: Identifying threatened populations and quantifying their vulnerability is crucial for establishing priorities for conservation and providing robust information for decision-making. Lahille’s bottlenose dolphins have been long subjected to by-catch mortality in gillnet fisheries in coastal waters of southern Brazil, particularly in the Patos Lagoon estuary (PLE) and adjacent coastal waters, where dolphins from three populations (or Management Units) show overlapping home ranges. In this study we used a stage-classified matrix population model to conduct a demographic analysis of the PLE’s population with life-history data estimated through an 8 years mark-recapture study. A population viability analysis (PVA) was used to run a series of simulations where the risk was assessed under different by-catch scenarios, taking into account the effects of parameter uncertainty and stochasticity in the projections. In the absence of by-catch, we estimated that this dolphin population would growth at a rate of about 3% annually (95% CI: 1.2–5.8%). Under current by-catch rates, prognoses indicated high probabilities of viability over the next 60 years. These optimistic prognoses appear to be associated with the high survival of adult females. However, the eventual removal of very few mature females (one every year or two) would result in a prominent likelihood of decline from its current abundance at all pre-specified levels. The viability of the population would be substantially improved if the survival of juveniles/sub-adults could be increased. This may be achieved through the recently implemented dolphin protection area, which prohibits gillnet fisheries in the core area of this population. If the protection area reduces the entanglement rates of the most impacted life-stages (i.e., juvenile/sub-adult dolphins), there would be a substantial chance of the PLE’s dolphin population increasing above 20% of its current size, which is here proposed as conservation goal. If met, this goal has the potential to promote habitat quality, increase genetic diversity and connectivity with adjacent populations, enhancing the ability of bottlenose dolphins in southern Brazil to cope with environmental change and potential disease outbreaks.

Kind regards,

Eduardo R. Secchi
Professor Associado
Laboratório de Ecologia e Conservação da Megafauna Marinha-Ecomega                                                                                                                                                                                                          Instituto de Oceanografia
Universidade Federal do Rio Grande-FURG
(53) 3233-6749 (53) 99945-3990
www.furg.br <http://www.furg.br/>

http://lattes.cnpq.br/2134644742559817 <http://lattes.cnpq.br/2134644742559817>
orcid.org/0000-0001-9087-9909 <http://orcid.org/0000-0001-9087-9909> 
ResearcherID: D-5038-2013
https://publons.com/researcher/ABF-1191-2020/ <https://publons.com/researcher/ABF-1191-2020/>

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