Post-Release Survival of Sailfish (Istiophorus platypterus) Captured on Commercial Pelagic Longline Gear in the Southern Gulf of Mexico

To estimate post-release survival of sailfish caught incidentally to regular commercial pelagic longline fishing operations in the southern Gulf of Mexico targeting mixed swordfish and tunas, ten pop-up satellite archival tags were deployed for ten days on incidentally captured animals. All ten tags transmitted following the full deployment period, transmitting 25-82% of the archived data. Repeated, short-duration movements at depth and horizontal displacement data from were consistent with survival of those nine of the ten animals for the ten-day deployment period. The results of this study indicate that sailfish can survive the trauma resulting from interaction with pelagic longline gear and that management measures promoting the release of sailfish from the pelagic longline fishery will reduce fishing mortality on the Atlantic sailfish stocks

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

Effects of Circle Versus J-style Hooks on Target and Non-Target Species in a Pelagic Longline Fishery

The U.S. Atlantic coastal pelagic longline fishery that targets tunas and swordfish also interacts with a wide range of non-target species including billfishes and sea turtles. Preliminary studies indicate that a change in terminal gear from J-style hooks to circle hooks may reduce bycatch mortality, but the effects of this change on catch rates of target species are unclear. To evaluate this, we monitored catch composition, catch rates, hooking location, and number of fish alive at haulback during 85 sets in the fall and spring seasonal fisheries from a commercial vessel operating in the western North Atlantic. Circle (size 16/0, 0° offset) and J-style (size 9/0, 10° offset) hooks were deployed in an alternating fashion. Hook–time recorders were used to assess time at hooking and temperature–depth recorders to measure gear behavior. Catch rates for most species categories were not significantly different between hook types (P \u3c 0.05), although circle hooks generally had higher tuna catch rates in the fall and lower swordfish catch rates in the spring. In the fall, both total catches and catches of pelagic rays were significantly higher on J-style hooks. Yellowfin tuna in the fall and dolphinfish in the spring caught on circle hooks were significantly larger than those caught on J-style hooks. In both seasonal fisheries, circle hooks caught fishes in the mouth more frequently than J-style hooks, which hooked more often in the throat or gut, although these differences between hook types were not statistically significant. Yellowfin tuna in the fall fishery were over four times more likely to be hooked in the mouth with circle hooks than with J-style hooks. Several target and bycatch species showed higher rates of survival at haulback with circle hooks, although only for dolphinfish in the fall fishery was this difference statistically significant. Our results suggest that the use of 0° offset circle hooks in the coastal pelagic longline fishery will increase the survival of bycatch species at haulback with minimal effects on the catches of target species

Strengthening Community Foundations - Redefining the Opportunities

Commissioned by the Council on Foundations and released in October 2003, this white paper details the findings and the implications of our study of costs and revenues at nine community foundations. Offering a new perspective for community foundation sustainability, the white paper proposes that community foundations examine their strategy and operations on a product-by-product basis, taking into account their mission-driven priorities, internal costs, customer preferences and the competing donor alternatives for each type of product or service they offer

Habitat Preferences and Diving Behavior of White Marlin (Tetrapturus albidus) Released from the Recreational Rod-and-Reel and Commercial Pelagic Longline Fisheries in the Western North Atlantic Ocean: Implications for Habitat-Based Stock Assessment Models

To improve billfish assessments, researchers have applied habitat-based models that incorporate behavioral and oceanographic parameters to standardize historical catch-per-uniteffort time -series data, accounting for significant gear changes over time. However, there has been little behavioral data from Atlantic billfishes to support these models. We provide information on habitat preferences of white marlin released from recreational and commercial fisheries in the western North Atlantic. White marlin were tagged with pop-up satellite archival tags (PSATs) from recreational rod and reel (n=22) and commercial pelagic longline (n=2) fisheries between May-November 2002. Our data indicate that each surviving white marlin spent the majority of time at depths of 10m or less, with all fish displaying repetitive short duration diving behavior (less than 30 minutes) to depths of 60-100m. These dives were presumably related to foraging activities. Furthermore, the depths of many of the repetitive dives were within the range of deep-set pelagic longline gear. Longline sets targeting bigeye tuna may actually increase white marlin by-catch by placing baits at depths where this species may be highly motivated to feed. Until billfish feeding motivation is better understood, it may be premature to apply habitat-based stock assessment models to billfishes in the Atlantic Ocean

Sailfish (Istiophorus platypterus) Habitat Utilization in the Southern Gulf of Mexico and Florida Straits with Implications on Vulnerability to Shallow-Set Pelagic Longline Gear

A total of 19 pop-up satellite archival tags (PSATs) were deployed on sailfish in the southern Gulf of Mexico between 2005 and 2007 aboard a commercial pelagic longline vessel (n = 18) and a recreational rod-and-reel vessel (n = 1). All PSATs were programmed to collect pressure (depth), temperature, and light-level data for 10 days at approximately 90-second intervals. These point-level data were not summarized prior to transmission, allowing the reconstruction of vertical movement patterns. Three tags suggested mortality events and were excluded from subsequent analyses. We present the preliminary data analyses from the remaining 16 PSATs. Sailfish are primarily associated with the upper surface waters at 20 m or less depth. However, sailfish also exhibited numerous repeated short-duration vertical movements below the local thermocline to depths of 50-150 m. The depth utilization from these tagged fish coincide with the actively fished depths of shallow-set pelagic longline gear, yet appear to be shallower than the depths of settled deep-set gear used to target bigeye tuna

Habitat Utilization and Vertical Movements of White Marlin (Tetrapturus albidus) Released from Commercial and Recreational Fishing Gears in the Western North Atlantic Ocean: Inferences from Short Duration Pop-up Archival Satellite Tags

behavioral and oceanographic parameters to standardize historical catch-per-unit-effort time-series data. These methods have allowed researchers to account for significant changes in the depths of pelagic longline (PLL) gear deployments over time. This study presents habitat-use data recovered from high-resolution 5- and 10-day pop-up satellite archival tags (PSATs) attached to 47 surviving white marlin released from commercial and recreational fishing gears offshore of the U.S. East Coast, the northern Caribbean, and Venezuela between 2002 and 2004. Data recovered from transmitting tags indicated that white marlin spent nearly half of their time associated with warm, near-surface waters (\u3c10 m). All fish displayed frequent short duration (mean: 39.8 min) vertical excursions from surface waters to depths averaging 51 m. Qualitative and multivariate classifications of data from completely transmitted movements of surviving white marlin revealed two major types of descents: one pattern was characterized by deep ‘V’-shaped excursions of relatively short duration (mean: 23.4 min) while the other featured descents that were more broadly ‘U’-shaped and confined to a specific depth range for an extended period of time (mean: 75.8 min). Based on the frequency, persistence, and patterns of these vertical movements, white marlin appear to direct a considerable proportion of foraging effort well below surface waters, a behavior that may account for relatively high catch rates of white marlin on some deep-set PLL deployments

Sailfish Habitat Utilization and Vertical Movements in the Southern Gulf of Mexico and Florida Straits

Pop-up satellite archival tags (PSATs) were deployed on 19 sailfish Istiophorus platypterus captured in the southern Gulf of Mexico and Florida Straits between 2005 and 2007 on commercial pelagic longline gear (n = 18) and recreational rod-and-reel gear (n = 1). The data from three tags indicated mortality events and were excluded from subsequent analyses. All PSATs were programmed to collect pressure (depth), temperature, and light-level data for 10 d at approximately 90-s intervals. These transmitted point data subsequently allowed the reconstruction of vertical movement patterns. The remaining 16 PSAT data sets indicate that sailfish are primarily associated with the upper surface waters within the top 20m(75.7% of total time during the day versus 46.7% at night) but undertake numerous short-duration vertical movements below the local mixed layer to depths of 50-150 m, presumably to feed. Analyses of 2,279 individual vertical movements among all 16 tagged sailfish indicated two distinct types (short-duration V and longer-duration U movements) similar to those reported for white marlin Kajikia albida. Sailfish also exhibited movement type differences between diel periods (having higher proportions of V movements in daytime), suggesting directed foraging at depth. Although short-duration movement to depths by these tagged fish contribute a small percentage of the total time at depth, these depths overlap with themonitored shallow-set pelagic longline gear depths actively targeting swordfish by the vessel in the local fishery. These results suggest that time-at-depth histograms alone may be insufficient to capture feeding motivations at depth and, therefore, true interaction potentials between individual sailfish and pelagic longline gear

Joint United States-Brazil Billfish Research in the Western South Atlantic

A joint research project between Brazilian and U.S. scientists was initiated in 2004 to investigate the interaction of istiophorid billfishes with pelagic longline fisheries in the western equatorial South Atlantic Ocean. This project incorporates two general themes (1) an investigation into several aspects of pelagic longline operations by comparing catch results between circle and “J” style hooks, time-of-capture with hook time recorders, and by direct monitoring of pelagic longline gear behavior, and (2) an additional evaluation of billfish trophic ecology using a combination of satellite tag technology and traditional analyses (e.g., gut contents and ageing). Data obtained from this research will provide additional data for the evaluation of habitat-based stock assessment modeling efforts for billfish and other pelagic fish species

Habitat Preferences of Istiophorid Billfishes in the Western North Atlantic: Applicability of Archival Tag Data to Habitat-Based Stock Assessment Methodologies

The Japanese pelagic longline fishery, which has a broad temporal and spatial coverage in the Atlantic Ocean, provides an important time series used in assessments of istiophorid billfishes. Past assessments of Atlantic blue marlin and white marlin by the ICCAT SCRS indicate a pronounced decrease in stock abundance of both species over the past fifty years. The current biomass of the white marlin is estimated to be 15% of that necessary for maximum sustainable yield (BMSY), while blue marlin are estimated to be at 0.4 BMSY. Over the past fifty years Japanese pelagic longline fishing operations have moved from shallow longline sets targeting yellowfin tuna to deeper longline sets targeting swordfish and bigeye tuna. As billfish are known to spend the majority of their time in surface waters, it was expected that billfish catch rates would be reduced for deeper set longlines. Coupled with the historical decrease in abundance of the stocks, the reduction of catch rates of deeper sets in recent years should be more pronounced. However, in some instances, billfish catch rates of deeper set longlines in recent years have exceeded those of shallow set longlines during times of higher billfish abundance. Such findings are enigmatic, and there are several possible explanations for the observed results (none of which are mutually exclusive): (1) the assessments may not be correct (billfish abundance may not be as low as it is currently estimated to be); (2) deep set longline hooks may fish at shallower depths than estimated; (3) the majority of billfish may be taken as deep set longlines are deployed and retrieved (a longer time for the bait to be moving through the water column); or (4) billfish may preferentially feed at depth. In this paper we provide detailed time-at-depth information for two blue marlin released alive from pelagic longline gear with pop-up archival satellite tags (PSATs) programmed to release from the animals after 30 days. Both blue marlin made several dives each day. The fish moved quickly to depth, and the times at depth were greater than those spent in descent or ascent. The depth of dives was greater during daylight hours. These data are suggestive of feeding excursions to deeper waters, movements for which these fish are well adapted with large eyes and a brain (eye) heating organ. If billfish undertake specific feeding movements to depth, then one would expect increased catch rates for deeply set longline gear. Researchers have recently attempted to standardize catch rates of billfish on pelagic longline for the time fish spend at depth (habitat-based models). However, if feeding motivation is not the same for an animal at all depths, then such standardizations will significantly bias catch rates and lead to errors in assessment