Chartered vessels:

F/V Captain Jack (Cruise 2000-1)

F/V Coast Pride (Cruise 2000-2)

F/V Sea Eagle (Cruise 2000-3)

F/V Excalibur (Cruise 2000-4)

The Fisheries Resource Analysis and Monitoring (FRAM) Division of the Northwest Fisheries Science Center (NWFSC) recently completed its third annual slope (100-700 fathoms) bottom trawl survey of the West Coast using local fishing vessels. This report summarizes the preliminary results from this survey.

The survey was conducted on board the chartered commercial trawlers Captain Jack and Coast Pride from June 28 through July 28, 2000 and the Sea Eagle and Excalibur from August 24 until September 24, 2000. These vessels began the cruise at Cape Flattery, Washington (48° 10’) and worked southward to Point Conception, California (35° 00’) sampling in predetermined areas and depths.

Groundfish slope surveys are designed to provide information on distribution and abundance of demersal species, and other biological resource information to assess the status of important fish stocks. During 1988-1997 and 1999-2000, the Alaska Fisheries Science Center (AFSC) Resource and Conservation Engineering (RACE) Division conducted similar surveys from the NOAA ship Miller Freeman. Our new survey effort from chartered vessels was designed as a new time series survey to obtain similar data, although not technically equivalent. The 2000 survey examined the feasibility of collecting biological information on all fish species and selected invertebrates. Specific objectives of the 2000 survey included:

1. Define the distribution and relative abundance of commercially important groundfish species particularly Dover sole (Microstomus pacificus), sablefish (Anoplopoma fimbria), longspine thornyhead (Sebastolobus altivelis), and shortspine thornyhead (S. alascanus) inhabiting depths from 100 fm to 700 fm.

2. Obtain biological data from groundfish species including length, weight, sex, and maturity.

3. Collect age structures from Dover sole, sablefish, longspine thornyhead, and shortspine thornyhead.

4. Quantify sampling effort by recording accurate net mensuration data on sampled hauls during the survey.

5. Compile other physical data (e.g. water temp) associated with groundfish abundance.

6. Collect special project samples or information.

The four vessels used in the charter ranged in length from 75 to 91 ft. (LOA) with vessel horsepower ranging from 425-850 hp. An experienced captain, two crew members, and three scientists staffed each vessel (Table 1). 

FRAM division provided standardized fishing gear for the survey. Each vessel used an "Aberdeen" style four panel bottom trawl with a small-mesh (2" stretched measure or less) liner in the codend in order to retain small organisms. The Aberdeen trawls were fitted with 8" and 10" rubber disc footropes and spread with 1200 lb. 5’ x 7’ steel Veedoors. A Simrad ITI trawl instrumentation system was employed on each haul to monitor trawl performance and ensure that the gear’s sampling efficiency was kept as constant as possible.

Sea surface temperatures were measured by using a bucket thermometer and sensors were placed on the trawl's headrope to record bottom temperature profiles.

The West Coast slope survey was designed primarily to assess the distribution and abundance of a wide range of commercially important finfish species. The 2000 survey was a combination of both systematic and random sampling strategies. Survey sampling locations were arranged along east-west transects with transects separated by 10 minutes of latitude. In total, there were 80 such transects covering the coast between the survey endpoints. At each transect, a total of 5 stations were selected from 2 categories: shallow (100-300 fms) and deep (300-700 fms). The stratum with the greatest linear distance was assigned 3 randomly selected depth ranges for sampling, while the category with least linear distance was assigned 2 randomly selected depths for sampling.

Each of the four vessels occupied a different subset of 20 transects separated by 40 minutes of latitude such that by the end of the survey all 80 transects had been sampled. Vessels started operation approximately at Cape Flattery, Washington and progressed southward down the coast completing the survey in Morro Bay, California.

The nominal duration of each haul was approximately 15 minutes long from the time the net was properly configured on the bottom until haul back. Captains were instructed to attempt to maintain a constant speed from 2.0 to 2.2 knots. Bottom contact sensors (Scott McEntire, AFSC/RACE Division, Seattle WA), placed on the footrope of the net, verified that the trawl was on the bottom and monitored the duration of the tow. Acoustic instruments attached to the net recorded various aspects of the net's mechanical performance. Other data were collected on the operational conditions (e.g. depth, amount of towing cable deployed, towing speed, tow duration, and weather conditions) and recorded on deck.

Catches were sorted to species or other appropriate taxon, then weighed. Samples were taken of the principal species for length-frequency determinations or acquisition of other biological data, using an electronic measuring board to log data. Following this, marketable fish were placed in the hold of the vessel, iced and delivered to a shoreside processing facility within 5 days. Such fish were part of the vessel’s compensation. All prohibited species and other marine organisms with no commercial value were returned to the sea.

A total of 325 stations out of 400 were successfully sampled (Table 2). Figure 1 identifies where successful and unsuccessful sampling occurred. To date, the 2000 slope survey has identified 210 species and additional biological information was gathered from 10 fish species. Table 3 illustrates the actual number by species of the approximately 65,000 total fish lengths and 6,000 total otoliths collected. The age structures will be examined and ages determined for these species at the Newport NMFS facility. 

The fifteen most prevalent species cruise-wide are listed in Table 4. Species catch units (kgs/haul) are aggregated by International North Pacific Fishery Commission (INPFC) area and primary depth statum of 100-300 fathoms and 301-700 fathoms on a haul by haul basis. In this report, no adjustments have been made in catch rates for variations in bottom time, but we will be evaluating this variable in the next phase of analysis.

Figure 2 is a coast wide summary of fish length-frequency distributions of 8 commercially important species. Figure 3 identifies the length-frequency distributions of 4 commercially important groundfish species (Dover sole, longspine thornyhead, shortspine thornyhead and sablefish) by INPFC area. Figure 4 and 5 further illustrate the different length-frequencies by sex and INPFC area for sablefish and Dover sole.