scholarly journals Analysis of marine mammal bycatch in the Uruguayan pelagic longline fishery operating in the Southwestern Atlantic Ocean

2015 ◽  
Vol 72 (5) ◽  
pp. 1637-1652 ◽  
Author(s):  
Cecilia Passadore ◽  
Andrés Domingo ◽  
Eduardo R. Secchi
Keyword(s):  
Atlantic Ocean ◽  
Marine Mammals ◽  
Population Decline ◽  
Additive Models ◽  
Longline Fishery ◽  
Southwestern Atlantic ◽  
Southwestern Atlantic Ocean ◽  
Pelagic Longline Fishery ◽  
The Impact ◽  
Pelagic Longline

Abstract Bycatch is one of the main causes of human-caused mortality and population decline of many marine mammals. Monitoring bycatch is the first step to understand the impact of the fisheries on the species affected. Understanding how the interaction between marine mammals and fishing operations varies in space and time, and how it is influenced by environmental variables, is essential for designing mitigation strategies to reduce bycatch mortality. In this paper, we use data gathered by scientific observers and a fishing skipper to analyse marine mammals bycatch by the Uruguayan pelagic longline fishery operating in the Southwestern Atlantic Ocean from 1996 to 2007. The total bycatch per unit effort (Bcpue) was 0.0150 marine mammals/1000 hooks and the highest values (∼0.2) were recorded between 37°–38°S and 49°–51°W. Total cetacean Bcpue during the study period was low (0.0051 cetacean/1000 hooks) and occurred between 32°–37°S and 46°–54°W. Generalized additive models showed that cetaceans' bycatch was mainly affected by the depth, sea surface temperature, and season. Although cetaceans were captured year-round, the highest values were registered in spring months, most bycatch events occurred over the continental slope (median = 619 m) and in waters with a median temperature of 19.7°C. The bycatch of pinnipeds was influenced by depth, location, and season. Pinniped bycatch occurred mainly in winter, in waters ranging from 80 to 5000 m of depth (median = 2366 m) between 34°–37°S (median = 35.9°S) and 54°–49°W (median = 51.8°W). The spatial analysis showed that most bycatch events occurred within the Brazil–Malvinas Confluence zone, an area of high productivity where the pelagic longline fleet concentrates its fishing effort and where marine mammals probably concentrate to feed.

scholarly journals Depredation by killer whale (Orcinus orca) and false killer whale (Pseudorca crassidens) on the catch of the Uruguayan pelagic longline fishery in Southwestern Atlantic Ocean

2015 ◽  
Vol 72 (5) ◽  
pp. 1653-1666 ◽  
Author(s):  
Cecilia Passadore ◽  
Andrés Domingo ◽  
Eduardo R. Secchi
Keyword(s):  
Atlantic Ocean ◽  
Killer Whale ◽  
Orcinus Orca ◽  
Longline Fishery ◽  
Southwestern Atlantic ◽  
Killer Whales ◽  
Southwestern Atlantic Ocean ◽  
Pelagic Longline Fishery ◽  
Pseudorca Crassidens ◽  
Pelagic Longline

Abstract This study analyses depredation by killer whales (Orcinus orca) and false killer whales (Pseudorca crassidens) on catches of the Uruguayan pelagic longline fishery in the Southwestern Atlantic Ocean between 1998 and 2007. Data were collected by scientific observers from the National Observer Program of the Tuna Fleet operating in the area between 19°–40.5°S and 20°–54°W. Depredation occurred in 67 of the 1029 sets and was restricted to the area from 25°–40.5°S to 27°–53°W, though larger proportions of depredation (DP: percentage of total fish caught damaged by cetaceans) were observed in the Brazil–Malvinas (Falkland) Confluence area (34°–37°S and 51°–53°W) where most of the fishing effort was concentrated. Depredation occurred year-round though intra-annual variability in its intensity was recorded. The overall DP was 0.37% and was slightly higher in autumn. The spatial analysis showed that DP within grids of 1 × 1° was homogeneous and generally <2.5%. Ten out of 57 fish species caught by the fishery were depredated by cetaceans. Swordfish (Xiphias gladius) showed the highest DP per species (1.17%). Using the frequency of resources selectivity index of Ivlev, it was determined that swordfish was selected as a preferred prey in 43.9% of the sets with depredation. Generalized linear models indicated that distance to coast, year, and vessel were significant variables in explaining the number of fish depredated per fishing event. The presence of killer whales in the fishing ground seems not to affect the catch per unit effort by the longline fishery. The losses caused by depredation of cetaceans on the catch are low with probably minor economic effects to the Uruguayan longline fishing industry.

A comparison of circle hook and J hook performance in a western equatorial Atlantic Ocean pelagic longline fishery

2011 ◽  
Vol 107 (1-3) ◽  
pp. 39-45 ◽  
Author(s):  
J.C. Pacheco ◽  
D.W. Kerstetter ◽  
F.H. Hazin ◽  
Humberto Hazin ◽  
R.S.S.L. Segundo ◽  
...  
Keyword(s):  
Atlantic Ocean ◽  
Longline Fishery ◽  
Equatorial Atlantic ◽  
Equatorial Atlantic Ocean ◽  
Pelagic Longline Fishery ◽  
Pelagic Longline

scholarly journals The missing whales: relevance of “struck and lost” rates for the impact assessment of historical whaling in the southwestern Atlantic Ocean

2020 ◽  
Author(s):  
Morgana Vighi ◽  
Asunción Borrell ◽  
Jennifer A Jackson ◽  
Emma L Carroll ◽  
Maria Grazia Pennino ◽  
...  
Keyword(s):  
Atlantic Ocean ◽  
Initial Population ◽  
Physeter Macrocephalus ◽  
Southwestern Atlantic ◽  
Sperm Whales ◽  
Right Whale ◽  
Eubalaena Australis ◽  
Southwestern Atlantic Ocean ◽  
Southern Right Whales ◽  
The Impact

Abstract The massive impact that open-boat historical whaling (18th to 20th centuries) had on whale populations has been traditionally estimated from records of oil and baleen plate production. However, an unknown proportion of hunted whales were struck, wounded, eventually killed, but lost, and not included in these records, suggesting that whaling impact may be critically underestimated. Whaling logbooks provide a key source for assessing past catches and losses. Here, we extract detailed records of 19875 days of activity in the southwestern Atlantic Ocean from 255 logbooks of offshore whaling voyages. During the period considered (1776–1923), whalers first targeted southern right whales (Eubalaena australis, 2497 sightings and 658 catches), gradually substituted by sperm whales (Physeter macrocephalus, 1157 sightings and 843 catches) after 1840. Loss rate factors, calculated to account for the number of “struck and lost” whales, decreased across time for both species, and were particularly high (ranging 1.09–1.6) for the southern right whale, whose population was drastically reduced by whaling, as compared to previous estimates based on rough catch records. Accurate accounting for these “lost” individuals is essential for reconstructing the impact of whaling on cetacean populations and for a proper assessment of their initial population size and demographic trends.

scholarly journals Characterization and comparison of Brazilian and foreign leased pelagic longline fleets in the Southwestern Atlantic Ocean between 2003 and 2014. How different are these fisheries?

2016 ◽  
Vol 5 ◽  
pp. 1-16
Author(s):  
Fernando Niemeyer Fiedler ◽  
Gilberto Sales ◽  
Bruno Barros Giffoni ◽  
Luiz Rodrigo Maçaneiro ◽  
Mariana de Karam e Britto ◽  
...  
Keyword(s):  
Atlantic Ocean ◽  
Steel Wire ◽  
Southwestern Atlantic ◽  
Wire Length ◽  
Target Species ◽  
Fishing Strategies ◽  
Southwestern Atlantic Ocean ◽  
Longline Fisheries ◽  
Pelagic Longline ◽  
Engine Power

The pelagic zone of the Southwestern Atlantic Ocean is an important area for longline fisheries. Brazilian waters are strategic regions for the performance of this modality in International Commission for the Conservation of Atlantic Tunas - ICCAT. In order to reach international quotas government strengthened its rent policy of foreign vessels aiming to promote technology transfer to the national fleet. Knowledge of vessel characteristics, technology used in equipment and strategies used by skippers are important for the management of this activity. The present study characterized vessels from national and foreign fleets operating out of the port of Itajaí, in the state of Santa Catarina (SC), between 2003 and 2014. Results indicate that these fleets are different in relation to size of vessels, engine power, cargo hold capacity, length of the main and branchlines, and steel wire length. Despite these differences, strategies adopted are critical to achieve better yields per trip. For the national fleet, the skills acquired to the use of equipments, in understanding the behavior of the target species, and change of fishing strategies often compensate for the lack of technology.

Assessing the impact of the pelagic longline fishery on albatrosses and petrels in the southwest Atlantic

2010 ◽  
Vol 23 (1) ◽  
pp. 49-64 ◽  
Author(s):  
Sebastián Jiménez ◽  
Martín Abreu ◽  
Maite Pons ◽  
Mauricio Ortiz ◽  
Andrés Domingo
Keyword(s):  
Longline Fishery ◽  
Southwest Atlantic ◽  
Pelagic Longline Fishery ◽  
The Impact ◽  
Pelagic Longline

scholarly journals An overview of the hooking mortality of elasmobranchs caught in a swordfish pelagic longline fishery in the Atlantic Ocean

2012 ◽  
Vol 25 (4) ◽  
pp. 311-319 ◽  
Author(s):  
Rui Coelho ◽  
Joana Fernandez-Carvalho ◽  
Pedro G. Lino ◽  
Miguel N. Santos
Keyword(s):  
Atlantic Ocean ◽  
Longline Fishery ◽  
Pelagic Longline Fishery ◽  
Pelagic Longline
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