| Abstrakt: |
Greater amberjack are active swimmers that occur over a range of depths around reefs and artificial structures. In this study, we describe overall diel patterns of depth use and swimming activity for greater amberjack. We tested for impacts of fishing-related stress on diel patterns, and we describe the potential influence of cyclonic storms on diel behavior and site attachment. Fifty-five fish were tagged with depth and accelerometer tags off coastal Alabama, USA, in three field efforts (FEs): FE1, summer–fall 2018; FE2, spring 2019; and FE3, summer–fall 2020. Fish displayed diel depth patterns that varied among individuals: fish that occupied a narrow depth range midway within the water column, fish that spent time both at mid-water and near bottom, and fish with more generalized patterns. Diel depth use was best predicted by both site depth and field effort, while swimming patterns were best predicted by field effort among tested factors: legal or sublegal sizes, field effort, site, and use of a descender device vs. surface release. Swimming activity was elevated on post-release days 1–5, consistent with predicted impacts of fishing stress. For most fish, however, depth use did not vary appreciably following release. Release with a descender did not prevent altered diel patterns, and thus, barotrauma was not likely a factor. Fish occupied shallower depths when Hurricane Laura (2020) passed south of the study area, and swimming activity was elevated during Hurricane Sally (2020). Our study highlights that depth use and swimming activity of greater amberjack are influenced by multiple factors and recreational fishing discards may impart sublethal stress that results in elevated swimming activity. [ABSTRACT FROM AUTHOR] |
Full text from SpringerLink