Research on rare and threatened species is often limited by access to sufficient individuals to acquire information needed to design appropriate conservation measures. Using a combination of data from pop‐up archival transmitting (PAT) tags across multiple institutional programmes, movements and habitat use of endangered smalltooth sawfish, Pristis pectinata were determined for animals from southern Florida and the Bahamas. All P. pectinata (n = 12) generally remained in coastal waters within the region where they were initially tagged, travelling an average of 80.2 km from deployment to pop‐up location. The shortest distance moved was 4.6 km and the greatest 279.1 km, averaging 1.4 km day‐1. Seasonal movement rates for females were significantly different with the greatest movements in autumn and winter. Pristis pectinata spent the majority of their time at shallow depths (96% of their time at depths <10 m) and warm water temperatures (22–28°C). Given sawfish show a degree of site fidelity punctuated by limited migratory movements emphasizes the need for conservation and management of existing coastal habitats throughout the species’ range.Published 2013. This article is a U.S. Government work and is in the public domain in the USA.

The scalloped hammerhead Sphyrna lewini and the great hammerhead S. mokarran are typically caught as bycatch in a variety of fisheries and are listed as globally Endangered by the International Union for the Conservation of Nature. Due to very high at-vessel mortality for these species, research is needed on fishing methods to reduce mortality for longline-captured sharks. A series of fishing experiments were conducted employing hook timers and temperature-depth recorders on contracted commercial vessels fishing with bottom-longline gear to assess factors related to mortality. A total of 273 sets were deployed with 54 485 hook timers. Scalloped and great hammerheads had at-vessel mortality rates of 62.9% and 56.0%, respectively. Median hooking times for scalloped and great hammerheads were 3.5 h and 3.4 h, respectively, and 50% mortality was predicted at 3.5 h and 3.8 h. When these data are considered for potential management strategies to reduce the mortality of hammerhead sharks, a limitation on gear soak time would probably improve hammerhead shark survivorship. However, it may prove to be difficult for a fishery to remain economically viable if the soak time is limited to less than the median hooking time for the target species. Additional management options, such as time/area closures, may need to be explored to reduce bycatch mortality of scalloped and great hammerheads.

Age and growth estimates for the dusky shark, Carcharhinus obscurus, were derived from vertebral centra collected in the northwestern Atlantic Ocean. Sample collection spanned the years prior to and following the implementation of management measures . Growth was compared pre-and post-population depletion and pre-and post-management to investigate the possibility of density-mediated shifts in age and growth parameters over time. There was no evidence of difference between periods for either sex. Additionally, bomb radiocarbon dating was used to determine the periodicity of band pair formation. Results support the traditional interpretation of annual band pairs up to approximately 11 years of age. After this time, vertebral counts considerably underestimate true age. Maximum validated ages were estimated to be between 38 and 42 years of age (an increase of 15 to 19 years over the band count estimates), confirming longevity to at least 42 years of age. Growth curves estimated using only validated data were compared to those generated using band pair counts. Logistic growth parameters derived from validated vertebral length-at-age data were L ∞ = 261.5 cm FL, L o =85.5 cm, t o =4.89 year and g= 0.15 year −1 for the sexes combined. Revised estimates of age at maturity were 17.4 years for males and 17.6 years for females.