link to AFSC home page

link to AFSC home page link to NMFS home page link to NOAA home page

Resource Ecology & Fisheries Management (REFM) Division

AFSC Quarterly
Research Reports
Apr-May-June 2011
ABL Reports
FMA Reports
HEPR Reports
NMML Reports
RACE Reports
REFM Reports
All Reports (.pdf)
Quarterly Index
Quarterly Home

Status of Stocks & Multispecies Assessment Program

Report on the Tenth Annual Republic of Korea – United States Fisheries Panel Conference

The Fisheries Panel of a Republic of Korea-NOAA Joint Project Agreement (JPA) holds an annual meeting to review progress in cooperative research on fisheries assessments and management issues. The JPA is an agreement to foster marine science and technology cooperation between the NOAA and two Ministries of the Republic of Korea (the Ministry of Land, Transportation, and Maritime Affairs and the Ministry of Food, Agriculture, Forestry, and Fisheries. The JPA is in its tenth year of implementation under the second 5-year plan. A new 5-year plan is under development to cover the period 2012–17.

This year's Fisheries Panel meeting was held at the AFSC on 22–23 June. The meeting is held as a conference where scientists from both sides report on cooperative research activities and associated research on fisheries assessments and management. The lead of the U.S. side (Patricia Livingston) and the ROK side (Dong Woo Lee) reaffirmed that the past year's cooperative activities have contributed to the scientific research of fisheries resources and their applications to fisheries management strategies for both countries.

By Loh-Lee Low and Julie Pearce

A Report on a Workshop Held at the ESSAS Symposium

Anne Hollowed (SSMA program) and Harald Loeng (Institute of Marine Research, Norway) co-chaired a workshop "Biological consequences of a decrease in sea ice in arctic and sub-arctic seas" as part of the "Comparative Studies of Climate Effects on Polar and Sub-Polar Ecosystems: Progress in Observation and Prediction" symposium sponsored by the Ecosystem Studies of Sub-Arctic Seas (ESSAS) program.

Thirty-four scientists from nine nations participated in the meeting. The purpose of the meeting was to assess which species would be likely to establish new breeding populations in regions of the Arctic and its surrounding shelf seas in response to the changes in summer sea ice. Scientists reviewed the life history and habitat associations of fish and shellfish and identified the characteristics of species that would be capable of shifting their range. Analysts then evaluated what biophysical changes would have to occur within Arctic ecosystems to support new species.

A list of candidate species was developed. An interesting outcome of the meeting was that it appears that the barriers to colonization of the Arctic by fish and shellfish from the Bering Sea are more substantial than the barriers in the Atlantic. Participants identified gaps in knowledge that are obstacles to predicting where and when new colonies would appear in the Arctic.

A list of key research activities needed to improve our predictive capability was discussed and supported. Four activities were particularly important. 1) Studies of the impact of climate change on the intrusion of Atlantic water into the Arctic and its shelf seas is needed. Most scientists considered this a key mechanism governing the colonization of Arctic regions by sub-Arctic species. 2) Studies of the role of seasonal light and ice on primary production and blooms are needed to evaluate how changes in timing will impact the fish/zooplankton phenology. 3) Research is needed to understand factors governing the timing and spatial extent of zooplankton production in the region including potential interactions between sub-Arctic and Arctic zooplankton. This research would improve our assessment of the prey limitations for pelagic fishes. 4) Periodic fish surveys are needed to monitor shifts in distribution and to improve our understanding of the zoogeography and species interactions in the region.

By Anne Hollowed

A Presentation on a Study to Determine if Acoustic Data can be used to Improve Trawl Survey Biomass Estimates

Paul Spencer gave a presentation titled "Can acoustic data be used to improve trawl survey biomass estimates of Alaska rockfish?" at the University of Washington Quantitative Seminar Series on 3 June. The presentation summarized research conducted with AFSC colleagues Dana Hanselman and Denise McKelvey on the use of hydroacoustics in improving trawl surveys for patchily-distributed rockfish. Survey biomass estimates of Alaska rockfish often show high variability, reflecting their “patchy” spatial distributions.

Several survey designs have been proposed for patchily-distributed species, including the Trawl and Acoustic Presence/Absence Survey (TAPAS) design in which hydroacoustic data are monitored in real-time to detect high-density patches that are then sampled at a higher rate than low-density background areas.  The research has three main objectives: 1) evaluate the TAPAS design in a rockfish survey; 2) conduct simulation modeling to evaluate how TAPAS might perform under a variety of conditions; and 3) analyze archived echosign data to identify patterns of rockfish spatial characteristics.

A rockfish survey was conducted in 2009 and showed a weak relationship between acoustic energy and trawl catches, resulting in an estimate of precision that was not higher than the precision from simple random sampling; however, a post-cruise analysis that applied an alternative patch definition resulted in some improvement in precision.

Simulation modeling indicates that the TAPAS design can perform well when a strong relationship exists between acoustic energy and trawl catches.  Because TAPAS is designed to sample each patch encountered, it also performs well when the population consists of many small patches rather than fewer but larger patches.  However, when a poor relationship exists between acoustic energy and trawl catches (as observed in the 2009 rockfish survey), TAPAS generally does not result in higher precision estimates than provided by simple random sampling.

Analysis of archived acoustic data from AFSC Gulf of Alaska groundfish surveys and the 2009 rockfish survey indicated a wide variety of rockfish aggregation patterns, including 'layer' aggregations that exceeded 800 m horizontally and smaller 'discrete' aggregations, and the rockfish aggregation patterns could not be distinguished from walleye pollock aggregation patterns.

The potential gains from the TAPAS design when a strong relationship exists between acoustic energy and trawl catches provides motivation to refine the relationship between these variables, particularly focusing upon isolating the portion of acoustic energy attributable to rockfish and quantifying the relative catchability of the trawl and acoustic gear.

By Paul Spencer

<<< previous

next >>>

            Home | FOIA | Privacy | | Accessibility      doc logo