Realm: Marine
Climate: Temperate/Tropical
Biome: Multiple ecoregions
Central latitude: 24.981493
Central longitude: -51.374069
Duration: 22 years, from 1973 to 2005

466437 records

540 distinct species

Across the time series Xiphius gladius is the most frequently occurring species

Methods

From May 1992 through December 2002. scientific observers associated with the SEFSC and NEFSC observed a total of 794 pelagic longline trips in waters of the northwest Atlantic Ocean (Table 1). In total. observers spent 10.613 days-at-sea during which 5.895 sets and 6.137 hauls were observed (Figure 2 and Table 1). POP procedure is to count any haul that is interrupted intentionally to allow the gear to soak longer. or that is interrupted for weather or mechanical problems for longer than 6 hours. as a ?split haul? (i.e. a single set that has two or more hauls associated with it). Further. during the 2001 NED experimental fishery each set was divided into 2 hauls. This accounts for the discrepancy between numbers of sets and numbers of hauls.Of the trips monitored. a total of 206 vessels were observed at least once during this time period. Data from 4 trips were excluded from analysis in this report because the gear was set as bottom longline and directed at shark species.Although a wide variety of fish were caught by the observed longline vessels. only about six species were routinely valued by the fishery as a marketable product. These primary species (swordfish. yellowfin tuna. bigeye tuna. bluefin tuna. mahi-mahi. and shortfin mako) comprise about 56% by number (N=120.295) of the total observed catch. Of the total observed fish (Figure 5). swordfish made up 30% by number of the catch; while yellowfin. bigeye. and bluefin tunas. combined. made up 18% by number of the observed catch. Sharks and rays. a bycatch of the tuna and swordfish fishery. made up the other major portion of the pelagic longline catch. about 29% by number.Observer coverage took place in all of the 11 geographical areas shown in Figure 1. As an overview of the observed longline gear deployed. the shortest average length of mainline set on an observed trip was 4.4 nautical miles (NM) while the longest average set during a trip was 46.6 NM. Additionally. during the 6.137 hauls observed. a total of 4.138.830 hooks were recorded (Table 1).The average minimum and maximum depths of the baited hooks are similar for the MAB. NEC. and NED (Table 5). with a range from 9 to 19 fathoms (17-35 m) for the three geographical areas. This represents the shallowest of the three general fishing depth groupings observed. Generally speaking. observed vessels fishing in the waters of the MAB and NEC target more on tuna species while the NED is typically directed more at swordfish (Fig. 6). The second grouping includes the GOM. FEC. SAB. and TUS. with a range of 18 to 36 fathoms (33-66 m). Vessels observed fishing in the waters off the southeast U.S. (FEC and SAB) and down below 5 degrees of North latitude (TUS) target mostly swordfish. with yellowfin generally found as a by-catch. whereas observed vessels in the GOM primarily target yellowfin tuna with a by-catch of swordfish. The deepest fishing depth grouping includes the CAR. SAR. NCA. and TUN with a range of 31 to 42 fathoms (57-77 m). Observed effort in these areas was almost completely directed at swordfish. These data suggest that fishing depths depends more on the area fished rather than target species. For example. observed hook fishing depth was shallowest in the NED and deepest in the CAR but in both areas the target species was swordfish. Unit of abundance = IndCountInt, Unit of biomass = NA

Citation(s)

"South Western Pacific Regional OBIS Data Asteroid Subset", NIWA (National Institute of Water and Atmospheric Research - New Zealand) MBIS (Marine Biodata Information System) accessed through South Western Pacific OBIS. Available at: http://www.iobis.org/mapper/?dataset=219, accessed 2012.