Nicholas M. Whitney

Group courtship, mating behaviour and siphon sac function in the whitetip reef shark, Triaenodon obesus

We analysed video records of three mating events involving nine free-living whitetip reef sharks in Cocos Islands, Costa Rica to examine reproductive behaviour in this species. We describe several behaviours never before documented in this species, and four behaviours never before documented in any elasmobranch. Here, we also present the first hypothesis for the function of the males paired reproductive organs, the siphon sacs, to be based on observations of mating sharks. We introduce terminology for three separate siphon sac structural components that are externally visible during courtship and mating in this species. Based on our analyses, as well as evidence from past mating studies, the siphon sacs in whitetip reef sharks appear to be used to propel sperm into the females reproductive tract, not for flushing the females reproductive tract of sperm from previous males. We discuss the implications of ‘group courtship’, ‘siphon isthmus constriction’, ‘reverse thrusting’, ‘postrelease gaping’ and ‘noncopulatory ejaculation’.

The physiological stress response, postrelease behavior, and mortality of blacktip sharks (Carcharhinus limbatus) caught on circle and J-hooks in the Florida recreational fishery

The views and opinions expressed or implied in this article are those of the author (or authors) and do not necessarily reflect the position of the National Marine Fisheries Service, NOAA. Abstract—The blacktip shark (Carcharhinus limbatus) is the most commonly captured species in the Florida recreational shark fishery. We aimed to quantify the postrelease mortality of blacktip sharks and to determine whether hook type (circle or J) had any impact on survival. We measured capture variables (e.g., fight time, animal condition, etc.), blood gas analytes, and finescale behavior obtained by using acceleration data loggers for blacktip sharks (n=31) caught on rod and reel by recreational fishermen. Mortalities (n=3; 9.7%) all occurred within 2 h after release. Surviving sharks were monitored for 7 to 72 h (mean: 30 h [standard deviation (SD) 22]) and behaviorally recovered from capture within 11 h (SD 2.6), although larger individuals recovered faster. Hook type did not affect where a shark was hooked, animal condition, the likelihood of hook removal, or recovery time. We found relatively low levels of mortality for blacktip sharks caught in the recreational fishery that were kept in the water and had not sustained serious injuries.