Tagging a speckled hind with a radio transmitter.<\/figcaption><\/figure>\n\n\n\nResearch Need<\/h3>\n\n\n\n Anglers and scientists often assume that survivorship of released snappers and groupers captured in deep water is nonexistent, because of pressure-related injuries (barotrauma) that the fish experience in which internal gas expansion prevents them from re-submerging on their own.<\/p>\n\n\n\n
For many years, venting \u2014 puncturing the swim bladder to release excessive air \u2014 was the go-to method for decompressing deepwater reef fish prior to release, but more recently the use of descending devices has emerged as the preferred approach. These devices allow anglers to rapidly return a fish to depth so that expanded gases quickly contract, without causing a flesh wound. Despite administering some tests to other species, researchers have never evaluated survivorship of deepwater groupers that were recompressed and released using descending devices.<\/p>\n\n\n\n
What did they study?<\/h3>\n\n\n\n Three species of deepwater grouper were the focus: scamp, snowy grouper and speckled hind. Researchers at North Carolina State University caught 19 groupers by traditional hook-and-line, fitted each fish with an ultrasonic telemetry tag \u2014 a small radio transmitter \u2014 and released each at depth using a SeaQualizer descending device.<\/p>\n\n\n\n
Next, they tracked short-term movements of the fish using electronic receivers. Each tag had a unique identification number and transmitted direction, speed and depth in real time. The scientists then produced an estimate of survivorship at the end of the two-week observation period.<\/p>\n\n\n\n
What did the results show?<\/h3>\n\n\n\n Researchers estimated survivorship at 50% but noted this calculation was very imprecise; there was a strong possibility that the rate of fish survivorship was between 10% and 90%.<\/p>\n\n\n\n
The precision of the estimated survival would improve if more fish were tested using this methodology. In this study, the survivorship estimate likely was biased on the low side, because, for methodological reasons, scientists had to assume that no fish shed its tag during the study. However, some tag shedding commonly occurs in studies like this.<\/p>\n\n\n\n
Regardless, the researchers\u2019 estimate is much higher than the 0% survivorship that managers often assume for these species.<\/p>\n\n\n\n
Anything else?<\/h3>\n\n\n\n Studies like this are valuable in that the results they generate likely will directly influence mathematical stock assessment models used to describe the health and status of these species. Those assessments tell us a lot and ultimately allow scientists and managers to determine how many fish we can catch (or release) without adversely impacting the resource.<\/p>\n\n\n\n
Reading<\/h3>\n\n\n\n Runde, Brendan J. and Jeffrey A. Buckel (2018). Descender Devices are Promising Tools for Increasing Survival in Deepwater Groupers<\/a>. Marine and Coastal Fisheries: Dynamics, Management, and Ecosystem Science<\/em>. 10:100\u2013117, 2018 doi: 10.1002\/mcf2.10010<\/p>\n\n\n\nSummary and photos by Scott Baker<\/em><\/p>\n\n\n\nThe text from Hook, Line & Science<\/em> is available to reprint and republish at no cost with this attribution: Hook, Line & Science<\/em>, courtesy of Scott Baker and Sara Mirabilio, North Carolina Sea Grant.<\/p>\n","protected":false},"excerpt":{"rendered":"The use of descending devices in offshore bottom-fishing can combat the potentially life-threatening effects on fish brought up from depth.<\/p>\n","protected":false},"author":89,"featured_media":414,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"ncst_custom_author":"","ncst_show_custom_author":false,"ncst_dynamicHeaderBlockName":"","ncst_dynamicHeaderData":"","ncst_content_audit_freq":"","ncst_content_audit_date":"","ncst_content_audit_display":false,"ncst_backToTopFlag":"","footnotes":""},"categories":[13,15,534,16,1],"tags":[],"class_list":["post-406","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-angler","category-fishing","category-fishing-gear","category-research","category-uncategorized"],"displayCategory":null,"acf":[],"yoast_head":"\n
Can Released Deepwater Grouper Survive? - Hook, Line and Science<\/title>\n \n \n \n \n \n \n \n \n \n \n \n\t \n\t \n\t \n \n \n \n\t \n\t \n\t \n