The NOAA IR serves as an archival repository of NOAA-published products including scientific findings, journal articles, guidelines, recommendations, or other information authored or co-authored by NOAA or funded partners.
As a repository, the NOAA IR retains documents in their original published format to ensure public access to scientific information.
i
Results of the 2016 and 2017 Central and Western Aleutian Islands underwater camera survey of Steller sea lion prey fields
-
2018
-
[PDF-18.57 MB]
Details:
-
Personal Author:
-
Corporate Authors:
-
NOAA Program & Office:
-
Description:Recent satellite tagging efforts indicate that foraging areas of endangered adult female Steller sea lions (SSL) in the central and western Aleutian Islands include shallow, nearshore regions. However, prey availability in these regions remains poorly understood because traditional bottom trawl surveys either cannot sample or lack precision on the rocky, nearshore habitats where sea lions forage. We attempted to overcome these sampling challenges by opportunistically deploying a towed underwater stereo-camera system near SSL rookeries and haulouts during the National Oceanic and Atmospheric Administration, Alaska Fisheries Science Center, Marine Mammal Laboratory’s ship-based population surveys of SSL in 2016 and 2017. A total of 63, 15-minute transects were conducted in depths ranging from 20 to 100 m. Fish and associated habitat were identified, quantified, and measured along transects. While stereo-image quality did not allow for the identification of all fish to the species level, it did allow for identification of many prey species (i.e., Atka mackerel (Pleurogrammus monopterygius), Pacific cod (Gadus macrocephalus)) and species groups (i.e., rockfishes, flatfishes, and sculpins) that are consumed by SSL during the summer. Camera transects encompassed substrates ranging from sand to high-relief boulder fields, and greater fish abundance was associated with rockier terrain. Substrates and associated fish abundances varied widely over small (10-100 m) spatial scales, suggesting that nearshore survey activities should be structured to account for extreme spatial variability. The relatively low cost of our camera system, combined with its ability to be deployed quickly during available vessel time, make it a promising tool for future fish surveys of nearshore and untrawlable habitat.
-
Keywords:
-
Series:
-
Document Type:
-
Place as Subject:
-
Name as Subject:
-
Rights Information:Public Domain
-
Compliance:Submitted
-
Main Document Checksum:
-
Download URL:
-
File Type:
