Patterns of movement, growth, and survival of adult sablefish (Anoplopoma fimbria) at contrasting depths in slope waters off Oregon

Abstract

Abstract-Demersal fish inhabiting continental slopes experience colder temperatures, increasing hydrostatic pressure, decreasing oxygen saturation, and decreasing productivity with increased depth. We examined depth-related patterns in smalland large-scale movement, growth, and relative survival of sablefish (Anoplopoma fimbria) tagged during 1996-2004 in Oregon waters at depths of 141-1225 m; 2614 of 17,400 fish were recaptured as of December 2016. Recapture rates indicated significant size-dependent mortality. Discard mortality was affected by surface temperature for small fish (<55 cm in fork length [FL]) from upper slope depths (<400 m). Depth effects on recapture rates reflected differences in fishing effort. Most recaptures were near the initial capture depth. Although 91% of the recaptures were within 200 km of the tagging location, some individuals migrated thousands of kilometers, reaching the western Aleutian Islands. Growth rates were faster for females than for males and decreased with depth. Sablefish in the deepest depths sampled had extremely slow growth rates (<2 cm FL/year), low dispersal (2.4%), and were largely female (81%). Prior studies of age distribution indicate that deep slope habitats also support greater longevity, potentially providing a refuge for older fish and a buffering effect to longevity overfishing, depending on spatial differences in exploitation rates.

What goes up must come down: Diel vertical migration in the deep‐water sablefish (Anoplopoma fimbria) revealed by pop‐up satellite archival tags

“…While DVM was frequently observed in the fish in the present study, it should be pointed out that these sablefish were collected at relatively shallow depths compared to the range of depths that sablefish inhabit. In tagging studies of sablefish off the coast of Oregon, Sogard and Berkeley () found that there was an increasing proportion of females as depth increased and a progressive decrease in growth. As depth increases, environmental conditions and food resources may alter the behavior of the sablefish and, thus, it is unclear whether sablefish inhabiting deeper water would exhibit the types of depth selection behavior as those shown here.…”

“…This may be a result of the potential to move great distances as adults (Hanselman, Heifetz, Echave, & Dressel, ), as well as movements that are part of the life history of younger sablefish (Maloney & Sigler, ). Adults are considered deep‐water inhabitants (Sasaki, ) and there appears to be a relationship between depth and size with larger fish living at greater depths (Afanasyev, Orlov, & Novikov, ; Laidig, Adams, & Samiere, ; Sogard & Berkeley, ). There also appears to be seasonal movement of adults to deeper water in the winter and shallower in the summer (Karinen, Barnett, & Masuda, ).…”

Advancing statistical models to reveal the effect of dissolved oxygen on the spatial distribution of marine taxa using thresholds and a physiologically based index

“…All alternative models included fixed effects of depth (represented as log(depth) and log(depth) 2 ) and year (as a categorical variable). These choices were based on the fact that adult sablefish generally show distinct depth preferences (Sogard and Berkeley 2017), and because overall sablefish density varies inter‐annually based on fluctuations in recruitment and mortality.…”

“…We evaluated the performance of alternative model formulations to determine how temperature and oxygen governs spatial distribution of sablefish Anaplopoma fimbria along the Pacific coast of the contiguous United States. Sablefish are the primary target in one of the most valuable finfish fisheries in this region (Krigbaum and Anderson 2021) and are potentially exposed to limiting levels of dissolved oxygen in this region because adult depth distribution (from roughly 200 to 1200 m; Sogard and Berkeley 2017) spans the oxygen minimum zone (Gilly et al 2013). Furthermore, in this eastern boundary current upwelling system, the ecosystem is regularly subject to low oxygen conditions (Chan et al 2008, Siedlecki et al 2016).…”

Status of sablefish, Anoplopoma fimbria, aquaculture

“…This may be a result of the potential to move great distances as adults (Hanselman, Heifetz, Echave, & Dressel, 2015) as well as movements that are part of the life history of younger sablefish (Maloney & Sigler, 2008). Adults are considered deep-water inhabitants (Sasaki, 1985), and there appears to be a relationship between depth and size with larger fish living at greater depths (Afanasyev, Orlov, & Novikov, 2014;Laidig, Adams, & Samiere, 1997;Sogard & Berkeley, 2017). There also appears to be seasonal movement of adults to deeper water in the winter and shallower in the summer (Karinen, Barnett, & Masuda, 2010).…”