Survival of white marlin (Tetrapturus albidus) released from commercial pelagic longline gear in the western North Atlantic

To estimate postrelease survival of white marlin (Tetrapturus albidus) caught incidentally in regular commercial pelagic longline fishing operations targeting swordfish and tunas, short-duration popup satellite archival tags (PSATs) were deployed on captured animals for periods of 5−43 days. Twenty (71.4%) of 28 tags transmitted data at the preprogrammed time, including one tag that separated from the fish shortly after release and was omitted from subsequent analyses. Transmitted data from 17 of 19 tags were consistent with survival of those animals for the duration of the tag deployment. Postrelease survival estimates ranged from 63.0% (assuming all nontransmitting tags were evidence of mortality) to 89.5% (excluding nontransmitting tags from the analysis). These results indicate that white marlin can survive the trauma resulting from interaction with pelagic longline gear, and indicate that current domestic and international management measures requiring the release of live white marlin from this fishery will reduce fishing mortality on the Atlantic-wide stock.

Toward identification of larval sailfish (Istiophorus platypterus), white marlin (Tetrapturus albidus), and blue marlin (Makaira nigricans) in the western North Atlantic Ocean*

The identification of larval istiophorid billfishes from the western North Atlantic Ocean has long been problematic. In the present study, a molecular technique was used to positively identify 27 larval white marlin (Tetrapturus albidus), 96 larval blue marlin (Makaira nigricans), and 591 larval sailfish (Istiophorus platypterus) from the Straits of Florida and the Bahamas. Nine morphometric measurements were taken for a subset of larvae (species known), and lower jaw pigment patterns were recorded on a grid. Canonical variates analysis (CVA) was used to reveal the extent to which the combination of morphometric, pigment pattern, and month of capture information was diagnostic to species level. Linear regression revealed species-specific relationships between the ratio of snout length to eye orbit diameter and standard length (SL). Confidence limits about these relationships served as defining characters for sailfish >10 mm SL and for blue and white marlin >17 mm SL. Pigment pattern analysis indicated that 40% of the preflexion blue marlin examined possessed a characteristic lower jaw pigment pattern and that 62% of sailfish larvae were identifiable by lower jaw pigments alone. An identification key was constructed based on pigment patterns, month of capture, and relationships between SL and the ratio of snout length to eye orbit diameter. The key yielded identifications for 69.4% of 304 (blind sample) larvae used to test it; only one of these identifications was incorrect. Of the 93 larvae that could not be identified by the key, 71 (76.3%) were correctly identified with CVA. Although identif ication of certain larval specimens may always require molecular techniques, it is encouraging that the majority (92.4%) of istiophorid larvae examined were ultimately identifiable from external characteristics alone.

Mitochondrial gene sequences useful for species identification of western North Atlantic Ocean sharks

Molecular-based approaches for shark species identification have been driven largely by issues specific to the fishery. In an effort to establish a more comprehensive identification data set, we investigated DNA sequence variation of a 1.4-kb region from the mitochondrial genome covering partial sequences from the 12S rDNA, 16S rDNA, and the complete valine tRNA from 35 shark species from the Atlantic fishery. Generally, within-species variability was low in relation to interspecific divergence because species haloptypes formed monophyletic groups. Phylogenetic analyses resolved ordinal relationships among Carcharhiniformes and Lamniformes, and revealed support for the families Sphyrnidae and Triakidae (within Carcharhiniformes) and Lamnidae and Alopidae (within Lamniformes). The combination of limited intraspecific variability and sufficient between-species divergence indicates that this locus is suitable for species identification.

Application of pop-up satellite archival tag technology to estimate postrelease survival of white marlin (Tetrapturus albidus) caught on circle and straight-shank (“J”) hooks in the western North Atlantic recreational fis

Short-duration (5- or 10-day) deployments of pop-up satellite archival tags were used to estimate survival of white marlin (Tetrapturus albidus) released from the western North Atlantic recreational fishery. Forty-one tags, each recording temperature, pressure, and light level readings approximately every two minutes for 5-day tags (n= 5) or four minutes for 10-day tags (n= 36), were attached to white marlin caught with dead baits rigged on straight-shank (“J”) hooks (n =21) or circle hooks (n=20) in offshore waters of the U.S. Mid-Atlantic region, the Dominican Republic, Mexico, and Venezuela. Forty tags (97.8%) transmitted data to the satellites of the Argos system, and 33 tags (82.5%) transmitted data consistent with survival of tagged animals over the deployment duration. Approximately 61% (range: 19−95%) of all archived data were successfully recovered from each tag. Survival was significantly (P<0.01) higher for white marlin caught on circle hooks (100%) than for those caught on straight-shank (“J”) hooks (65%). Time-to-death ranged from 10 minutes to 64 hours following release for the seven documented mortalities, and five animals died within the first six hours after release. These results indicate that a simple change in hook type can significantly increase the survival of white marlin released from recreational fis

Historical Catches of Humpback Whales, Megaptera novaeangliae, in the North Atlantic Ocean: Estimates of Landings and Removals

Whaling for humpback whales, Megaptera novaeangliae, in the North At- lantic Ocean has occurred in various forms (e.g. for local subsistence, for oil to be sold commercially, using hand harpoons and deck-mounted cannons, using oar-driven open boats and modern powered catcher boats) from the early 1600’s to the present. Several previous attempts to estimate the total numbers of humpback whales removed were considered close to comprehensive, but some uncertainties remained. Moreover, the statistical uncertainty was not consistently presented with the previous estimates. Therefore, we have pursued several avenues of additional data collection and conducted further analyses to close outstanding data gaps and address remaining issues. Our new estimates of landings and total removals of humpback whales from the North Atlantic are 21,476 (SE=214) and 30,842 (SE=655), respectively. These results include statistical uncertainty, reflect new data and improved analysis methods, and take account of some fisheries for which estimates had not been made previously. The new estimates are not sufficiently different from previous ones to resolve the major inconsistencies and discrepancies encountered in efforts to determine the conservation status of humpback whale populations in the North Atlantic.

Spatial and Temporal Distribution of Sea Turtles in the Western North Atlantic and the U.S. Gulf of Mexico from Marine Recreational Fishery Statistics Survey (MRFSS)

Systematic surveys, along with opportunistic sightings, have provided important information on sea turtle (Cheloniidae and Dermochelydae) distributions, knowledge which can help reduce the risk of harmful human interaction. In 1991 and 1992, the Marine Recreational Fishery Sta- tistics Survey (MRFSS) of the National Ma- rine Fisheries Service, NOAA, provided a unique opportunity to gain additional, synoptic information on the spatial and temporal distribution of sea turtles along the U.S. Atlantic and Gulf of Mexico coasts by asking recreational anglers if they had observed a sea turtle on their fishing trip. During the spring and summer months of those years, as water temperatures warmed, the MRFSS documented an increase in sea turtle sightings in inshore waters and in a northward direction along the U.S. Atlantic Coast and in a westward direction along the northern Gulf of Mexico. This pattern reversed in the late summer and fall months as water temperatures cooled, with sea turtles concentrating along Georgia and both coasts of Florida. Although the MRFSS did not provide species or size composition of sea turtles sighted, and effort varied depending upon location of fishing activity and time of year anglers were queried, it did provide an additional and useful means of ascertaining spatial and temporal distributions of sea turtles along these coasts.

Blue Marlin, Makaira nigricans, Movements in the Western North Atlantic Ocean: Results of a Cooperative Game Fish Tagging Program, 1954-88

Blue marlin, Makaira nigricans, tag and recapture data are summarized for 1954-1988. During this period, 8,447 fish have been tagged and only 30 (0.35 percent) have been returned. Results of the tagging program indicate that blue marlin not only travel considerable distances (7,OOO km from the U. S. Virgin Islands to the Ivory Coast of West Africa), but have remained at large for up to 8 years. Seasonal movements, however, are difficult to determine accurately.

Food habits of Sowerby's beaked whales (Mesoplodon bidens) taken in the pelagic drift gillnet fishery of the western North Atlantic

We describe the food habits of the Sowerby’s beaked whale (Mesoplodon bidens) from observations of 10 individuals taken as bycatch in the pelagic drift gillnet fishery for Swordfish (Xiphias gladius) in the western North Atlantic and 1 stranded individual from Kennebunk, Maine. The stomachs of 8 bycaught whales were intact and contained prey. The diet of these 8 whales was dominated by meso- and benthopelagic fishes that composed 98.5% of the prey items found in their stomachs and cephalopods that accounted for only 1.5% of the number of prey. Otoliths and jaws representing at least 31 fish taxa from 15 families were present in the stomach contents. Fishes, primarily from the families Moridae (37.9% of prey), Myctophidae (22.9%), Macrouridae (11.2%), and Phycidae (7.2%), were present in all 8 stomachs. Most prey were from 5 fish taxa: Shortbeard Codling (Laemonema barbatulum) accounted for 35.3% of otoliths, Cocco’s Lanternfish (Lobianchia gemellarii) contributed 12.9%, Marlin-spike (Nezumia bairdii) composed 10.8%, lanternfishes (Lampanyctus spp.) accounted for 8.4%; and Longfin Hake (Phycis chesteri) contributed 6.7%. The mean number of otoliths per stomach was 1196 (range: 327–3452). Most of the fish prey found in the stomachs was quite small, ranging in length from 4.0 to 27.7 cm. We conclude that the Sowerby’s beaked whales that we examined in this study fed on large numbers of relatively small meso- and benthopelagic fishes that are abundant along the slope and shelf break of the western North Atlantic.

Use of skeletochronological analysis to estimate the age of leatherback sea turtles Dermochelys coriacea in the western North Atlantic

Although growth rate and age data are essential for leatherback management, estimates of these demographic parameters remain speculative due to the cryptic life history of this endangered species. Skeletochronological analysis of scleral ossicles obtained from 8 captive, known-age and 33 wild leatherbacks originating from the western North Atlantic was conducted to characterize the ossicles and the growth marks within them. Ages were accurately estimated for the known-age turtles, and their growth mark attributes were used to calibrate growth mark counts for the ossicles from wild specimens. Due to growth mark compaction and resorption, the number of marks visible at ossicle section tips was consistently and significantly greater than the number visible along the lateral edges, demonstrating that growth mark counts should be performed at the tips so that age is not underestimated. A correction factor protocol that incorporated the trajectory of early growth increments was used to estimate the number of missing marks in those ossicles exhibiting resorption, which was then added to the number of observed marks to obtain an age estimate for each turtle. A generalized smoothing spline model, von Bertalanffy growth curve, and size-at-age function were used to obtain estimates of age at maturity for leatherbacks in the western North Atlantic. Results of these analyses suggest that median age at maturation for leatherbacks in this part of the world may range from 24.5 to 29 yr. These age estimates are much greater than those proposed in previous studies and have significant implications for population management and recovery.

A remarkable new species of Psednos (Teleostei: Liparidae) from the western North Atlantic Ocean

Psednos rossi new species (Teleostei: Liparidae) is described from two specimens collected in the North Atlantic Ocean off Cape Hatteras, North Carolina, at depths of 500–674 m. Psednos rossi belongs to the P. christinae group, which includes six other species and is characterized by 46–47 vertebrae and the absence of a coronal pore. Psednos rossi differs from those six species by having characters unique within the genus: straight spine, body not humpbacked at the occiput, and a very large mouth with a vertical oral cleft. Other distinguishing characters include a notched pectoral fin with 15–16 rays, eye 17–19% SL, and color in life orange-rose. With P. rossi, the genus Psednos as currently known includes 26 described and five undescribed species of small meso- or bathypelagic liparids from the Atlantic, Pacific, and Indian Oceans.