Complex Dispersal of Adult Yellowfin Tuna From the Main Hawaiian Islands

Abstract

Local availability of yellowfin tuna, Thunnus albacares, is a key economic, dietary and cultural concern for Main Hawaiian Islands (MHI) communities and insular fisheries. Consequently, interactions of inshore vs. offshore fisheries and connectivity to yellowfin elsewhere in the Pacific remain important scientific management questions. Local fisheries target adult tuna during the summer months, but subsequent tuna movements, presumably away from the islands after reproduction ceases, remain undocumented. From 2014 to 2016, we partnered with local fishermen to catch and release nineteen yellowfin tuna (41-91 kg, estimated whole weight) off Kaua'i, with popup satellite archival tags programmed for 9-12-month missions. Although data collection periods did not exceed 59 days mainly because of tag hardware failures and predator interactions, short tracks revealed diverse patterns: local residency for some individuals, and rapid, long-distance (>800 km) dispersals in multiple directions for others. Adult yellowfin tuna frequenting the MHI have more complex movements than previously assumed. Despite being a nursery area, whether the assemblage is entirely produced and retained in the region is not resolved. However, attaining 1-year migration records requires tag performance that was not achieved by the deployed tags. It remains a prerequisite for greater understanding of yellowfin in the Main Hawaiian Islands and Central North Pacific, including assessment of their spatial connectivity, impacts of climate change, and shifting ecosystems.

Connectivity of Striped Marlin From the Central North Pacific Ocean

“…Tag failure, as reported in this study and others (e.g. Lam et al, 2020), has increasingly become a costly impediment to our ability to track and observe billfish and tuna (Musyl et al, 2011;Lutcavage et al, 2015). To ensure the least amount of bias introduced into stock assessment and fisheries management, stakeholders must encourage tag manufacturers to provide reliable products with consistent performance, and push for innovation in tracking technologies so that research dollars can be spent most effectively.…”

Estimating post-release mortality of long-line caught tropical tunas in the Pacific Ocean

“…Other studies of tagged tuna captured by rod and reel also indicate that tagging itself does not result in high levels of mortality (e.g. Lam et al 2020Tolotti et al 2020, and lab studies also showed no survival or behavioural impacts of satellite tagged, captive mahimahi (Coryphaena hippurus) compared to untagged conspecifics (McGuigan et al 2021). It appears that the commercial longline hauling is more responsible for the high mortality we have observed, rather than the satellite tagging procedure itself.…”

Spatial Dynamics and Fine-Scale Vertical Behaviour of Immature Eastern Australasian White Sharks (Carcharodon carcharias)

“…Additionally, 57% of tags deployed in this study did not report. Having more than half of the total number of purchased tags as non-reporting was not only financially expensive but also resulted in significant loss of scientific opportunity, as has repeatedly been reported in PSAT studies e.g., [ 11 , 41 , 42 ]. In terms of seasonal analysis, it prevented us from attaining equal numbers of tracks per month, which would have been necessary to fully characterise seasonal patterns.…”