Development of a combined hydroacoustic and visual survey to determine regional population size of nearshore rockfish important to recreational and commercial West Coast fisheries

Identification Information

Citation

Originator: Marine Resources Program: Marine Fisheries Research & Marine Habitat

Publish Date: 2022

Online Link: https://doi.org/10.1093/icesjms/fsab245

BPA Project #:

Contact Information

Agency: Oregon Department of Fish and Wildlife

Name: Leif Rasmuson

Job Position: Marine Fisheries Research Project Leader

Telephone: 541-270-5561

E-Mail Address: leif.k.rasmuson@odfw.oregon.gov

Description

Abstract: The purpose of this proposed project is to further the development of a novel nearshore fishery-independent survey to improve assessment and sustainable management of nearshore rocky reef fish stocks off of Oregon. The specific goal is to gather detailed data to inform the selection of the optimal combination of visual survey tools and hydroacoustic data collection for quantifying nearshore rocky reef fish abundance and biomass, with a focus on the semi-pelagic rockfish species that are most critical to Oregon’s coastal communities. There are two specific objectives for this project. Objective 1: Assess the effectiveness of paired acoustic and pelagic drop-camera surveys for documenting semi-pelagic rockfish density and biomass. MRP has developed a pelagic drop-stereo camera system specifically to provide species and length compositions to compliment acoustic data collection. However, specific deployment strategies to accurately assess these compositions throughout the water column have not yet been evaluated. This objective would be to test multiple deployment strategies of the pelagic drop-camera by targeting schools of semi-pelagic rockfishes and compare species compositions and length distributions from each deployment strategy. Objective 2: Assess the importance of near-bottom fish (including target species and non-target species) for interpretation of acoustic-based abundance estimates. Evaluate the ability of three visual survey tools (drop-camera, lander, ROV) to quantify the contribution of these fish to total abundance for target species. While the pelagic drop-camera has been developed specifically for use with the acoustic system, there is strong potential for bias in its sampling frame, as it is geared towards mid-water column data collection, and therefore may underestimate abundance and bias species compositions by not sampling near-bottom species that are acoustically detected. Additionally, an inherent feature of acoustic data collection is the presence of a near-bottom “dead zone” in high relief habitat. MRP has two tools, an ROV and a rugged, stationary video lander, that are capable of capturing species composition and length distributions of benthic fish, including those adjacent to or within the acoustic dead zone. By evaluating each of these tools, in concert with the acoustic and pelagic drop-camera combination, a more complete picture of the species present will be provided and would quantify the importance of regularly sampling the benthos during a nearshore survey. To evaluate this objective, multiple reefs will be surveyed with all four sampling tools. Densities of near-bottom fish will be compared from all three tools or tool combinations, and sampling area population estimates will be produced. Anticipated Benefits/Outcomes Taken together, results from these two objectives would inform the design and implementation of a wide-scale nearshore fishery-independent survey. The first objective will provide information on the optimal deployment strategy for the pelagic drop-camera, and if that deployment strategy might need to be modified in different locations along the Oregon coast due to differing species compositions or semi-pelagic school structure. The second objective will provide information on whether an additional tool that evaluates the benthic component, both within the acoustic dead zone and outside the scope of the pelagic drop-camera, is needed. This will provide information on how critical this benthic component is to regularly sample as part of a comprehensive, wide-scale nearshore survey, and would provide information if the importance of the benthic component may vary by location or site characteristics. Finally, comparisons between the two benthic tools will provide support for the most appropriate tool to use with the acoustic and pelagic drop-camera combination, if necessary. This objective will also allow for evaluation of the size and importance of the acoustic dead zone, and how that feature might vary in multiple types of terrain present off the Oregon coast. The information provided from this pilot study would allow ODFW to effectively plan and implement a comprehensive nearshore fisheries-independent survey in the near future. In the short term, this project would directly increase knowledge of nearshore fish behavior and habitat associations, and particularly provide additional information about nearshore species that are currently extremely data-limited. Eventually, the full implementation of a nearshore fishery-independent survey would provide unbiased estimates of abundance and biomass for multiple nearshore species, including those critically important to the coastal community. This fishery-independent survey will be especially important for the most heavily fished species, such as the semi-pelagic black, blue and deacon rockfishes. Improvement of nearshore stock assessments will provide benefits to both commercial and recreational fishermen, and to coastal communities that rely on those industries, by promoting the long-term, sustainable management of these species, and increase public confidence in stock assessments, which is key to successful management.

Purpose: Second URL for reports: https://doi.org/10.1093/icesjms/fsac138

Time Period of Content: 01/01/2017-10/31/2018

Geographic Extent: Oregon Nearshore (Redfish Rocks Reef, Orford Reef, Bandon Reef, Cape Arago, Cascade Head)

Status: Final

Use Constraints:

Format: PDF

Data Quality Information

Lineage-Source: Grant number NA17NMF4270223. The data (up to 2 TB total) underlying this article will be shared on reasonable request to the contact person. Open access manuscripts from this study can be found at ICES Journal of Marine Science in URL's at the top of this record.

Data Information

No data information was supplied.

Entity and Attribute Information

Attributes Description: Field attribute information is available in the attached file(s).

Is a physical copy maintained for reference at Headquarters? Unknown