Conservation Lecture Series
Thursday, September 12, 2013 -- 7 p.m.
Fishing effort for deep-water sharks, both targeted and incidental, has been increasing worldwide over the last few decades despite a lack of biological information for most of these rare species.
Providing life history data for these deep-sea predators is crucial for fisheries management and for advancing the overall understanding of deep-sea ecosystems. Most commonly encountered shark species can be aged by examining calcified growth bands within the vertebral centra, much like growth rings in tree trunks. Since vertebral cartilage is generally uncalcified in deep-water sharks, the dorsal finspine presents an alternate structure that can be used to determine age for some of these species. Reproductive output (e.g. fecundity, seasonality, ovarian cycle) is an equally important component of shark life history, yet this information remains largely unknown for most deep-water shark species.
Recent deep-sea expeditions and long-term studies, such as the Deep-C Consortium, have afforded researchers rare opportunities to study these rare deep-water species in great detail. Results of these life history studies (specifically age, growth and reproduction) have confirmed that many of these species are among the slowest growing of all vertebrates, characterized by late maturity, low fecundity, high longevity and slow growth.
With such conservative life histories, these species are not resilient to extensive harvest and are therefore prone to over-exploitation and localized depletion in those areas where they are harvested.