Obsolete - AFSC/RACE/EcoFOCI - Trawl catch data collected in support of FOCI assessment surveys and ecosystem observations in the Bering Sea and the Gulf of Alaska 1993 to Prese...

The trawl database contains multiple tables of data. The ‘haul’ table contains the location, date, time and depth of the trawl haul. The ‘catch’ table contains the numbers and weights of the taxa in each haul. The ‘length’ table contains the lengths of selected taxa in each haul. There is data for the eastern Bering Sea for 2008, 2010, 2012, and 2014. There is Gulf of Alaska trawl data from 1993 to 2015.

The trawl dataset was developed to archive data from juvenile fish trawl surveys, including trawl locations dates, and times, catch data and length data. These data are used in studies of fish abundance, distribution, condition, and diet to better understand recruitment dynamics.

Supplemental Information - Data Parameters and Units - Descriptive Information about the Data Parameters and Units.

Year of trawl, month of trawl, date of haul, latitude (degN) of trawl deployment, latitude_(minN) of trawl deployment, longitude_(degW) of trawl deployment, longitude_(minW) of trawl deployment, time of trawl equilibrium (gmt_time), equilibrium_latitude_(degN), equilibrium_latitude_(minN), equilibrium_longitude_(degW), equilibrium_longitude_(minW), equilibrium_wire_out_(m), equilibrium_headrope_depth_(m), equilibrium_netmouth_height_(m), equilibrium_bottom_depth_(m), equilibrium_sea_surface_temperature_(degC), equilibrium_water_temperature_at_gear_depth_(degC), time of haulback_(gmt), haulback_latitude_(degN), haulback_latitude_(minN), haulback_longitude_(degW), haulback_longitude_(minW), gear_retrieved_(gmt), gear_retrieved_latitude_(degN), gear_retrieved_latitude_(minN), gear_retrieved_longitude_(degW), gear_retrieved_longitude_(minW).

Catch taxa common name, catch taxa sample weight_units (kg or g) catch taxa non_subsample_weight (in units of previous column), subsample_weight (in units of previous column), subsample_count (number of individuals).

Lengthed fish common_name, lengthed fish length_type (standard length, fork length, or total length), frequency (number of fish in this length increment), length_(mm).

Supplemental Information – Methods - Descriptive Information about the methods used.

Bering Sea cruises:

Fish were collected using a 3.05-m plumb staff beam trawl with 7-mm mesh and 4-mm codend liner (after Gunderson and Ellis, 1986). In 2003, the trawl had additional 15 cm lengths of hanging chain attached every 15 cm on the lead-lined footrope. In 2008 and 2010, the trawl was equipped with an extended top panel to increase catchability of gadiform fish, as described by Abookire and Rose (2005). In 2003, tows were made in daylight (08:00–20:00 h). In 2008 and 2010, tows were conducted at all hours of the day and night. Towing speed was 0.5 m s21 (1.0 knot) in 2003, and 1 m s21 in 2008 and 2010. The vessels maintained a single heading during tows; beginning and ending positions of each tow were recorded using standard global positioning systems (GPSs) and used to calculate distance towed. Depth was recorded from the depth sounder on the vessels. Tows were of variable distance (122–1000 m in 2003, 240–1400 m in 2008, and 138–797 m in 2010). Target tow durations were 10 min in 2003, and 20 min in 2008 and 2010, but in areas with high catches, subsequent tows were shortened to reduce risk of catch spilling out of the net mouth. Catch-per-unit-effort (cpue) of age-0 and age-1 northern rock sole for each tow was calculated as number of fish caught divided by the area swept by the trawl, i.e. distance towed multiplied by the effective net width (3.05 m beam length × 74%; Gunderson and Ellis, 1986). A vertical profile of hydrographic data was recorded at each station using a conductivity, temperature and depth (CTD) profiler (Sea-bird Electronics, SBE 19 in 2003, SBE 19 plus in 2008, and SBE 39 in 2010). In 2003, the CTD profiler was deployed at the bottom of the ship’s wire, and data were collected on each downcast. In 2008, the CTD profiler was attached above a bongo net, and data were collected on each upcast. In 2010, the temperature profile and bottom temperature were recorded using an SBE 39 temperature profiler attached to the beam of the beam trawl. Bottom temperatures were interpolated for mapping using the inverse distance weighted (IDW) tool in ARCMAP 9.3 (ESRI).

In 2003 and 2010, total length (TL) of northern rock sole was recorded to the nearest mm. In 2008, northern rock sole were measured to standard length (SL) if ,80 mm SL and to TL if .80 mm SL. Standard lengths were converted to total lengths using conversion

factors developed by measuring both standard and total length of frozen northern rock sole. For fish ,40 mm SL, the conversion factor was TL ¼ 1.2044(SL) + 0.0415, r2 ¼ 0.95, n ¼ 120; and for fish .40 mm SL, the conversion factor was TL ¼ 1.231(SL) –

1.325, r2 ¼ 0.99, n ¼ 106. In all years, subsamples of at least 25 fish were measured if a size class of fish contained too many individuals to measure in the available time.

Gulf of Alaska cruises

Midwater trawl

The Stauffer (a.k.a., anchovy) trawl was deployed to a depth of 200 meters, or 10 meters, off the bottom, whichever is shallowest. Net depth was monitored using the ship’s Simrad ITI (trawl eye) or FURUNO system. Standard trawl operations were used for deployment. Once equilibrium was achieved, as determined by the fishing officer or scientist, the trawl was retrieved at a wire rate of about 10 meters per minute. Thus, the trawl was usually be fished over a double-oblique path. Occasionally, the trawl was used to target a specific depth. In this case, standard trawl deployment and retrieval was used.

Walleye pollock (all age classes), Pacific cod, capelin, eulachon, and flatfishes were sorted from the catch. It was sometimes necessary to sort walleye pollock into ca. <120 mm SL and ca. >12 cm FL to ensure adequate representation of age-0 and age-1+ components, respectively, in the catch and length data. Flatfishes were sorted to species. For each of these groups, all individuals or a randomly drawn subsample of all individuals was used to determine length composition. For walleye pollock, approximately 100 age-0 and 100 age-1+ walleye pollock were measured for body length. Standard length (SL) is the body-length metric for age-0 walleye pollock. Fork length (FL) is the body-length metric for age-1+ walleye pollock. Subsampling may have been necessary prior to enumerating and measuring individuals. A sample of each of the following groups were frozen for subsequent examination in the laboratory: age-0 walleye pollock, age-0 Pacific cod, age-0 and age-1 yellowfin sole, and each of the other flatfish species (age-0 only). These were flash frozen in the –80 oC freezer and then moved to the –20 oC freezer.

3-m Beam Trawl

A modified plumb-staff, 3-m beam trawl was deployed to collect juvenile flatfishes from the seafloor. Flatfishes, Pacific cod and walleye pollock were the priority for catch processing, other fishes were sorted to the finest taxonomic level practical and then will be enumerated and weighed and the discarded (but see Special Projects). None of the invertebrate portion of the catch was quantified. Flatfish juveniles, walleye pollock, and Pacific cod were sorted to species, then counted, weighed, and lengthed. If catch of any one target species is very high (more than 50 individuals of one species), a subsample was taken for counting and weighing, and the remainder of the sample was weighed and frozen or discarded. After counting and weighing, the fish (age-0 walleye pollock, age-0 Pacific cod, age-0 and age-1 yellowfin sole, and age-0 individuals of all other flatfish species) were put into individual freezer bags (1 bag per species) and put in the -80 C freezer in the rough lab.

Supplemental Information – Instruments - Descriptive Information about the instruments and equipment used.

The beam trawl is a small trawl to sample fish and invertebrates. The basic design is detailed in Gunderson and Ellis (1986), but with a modified bridle and added top panel as described in Abookire and Rose (2005), the trawl has improved catch efficiency of fish that are further off bottom than juvenile flatfish. The trawl may be fished over soft bottom with either a tickler chain in front of the footrope (Gunderson and Ellis 1986), or over somewhat more rocky bottom with the tickler chain removed and additional ground gear consisting of a 10.2-cm rubber disks over a steel chain attached to the footrope in 10 places (Abookire and Rose 2005). For fishing from a large vessel, a steel beam is used in place of the aluminum beam, with extra flotation provided by a seine float over each side of the beam.

1. Figure 1. Schematic of the beam trawl described in Gunderson, D. R., and I. E. Ellis (1986) Development of a plumb staff beam trawl for sampling demersal fauna. Fisheries Research 4:35-41. Trawl modified in Abookire, A. A. and C. S. Rose (2005) Modification to a plumb staff beam trawl for sampling uneven, complex habitats. Fisheries Research 71:247-254.

In Figure 1, the top diagram is the trawl viewed from above, the lower right diagram is the trawl viewed from the side of the wing, and two enlargements of the trawl footrope options are in the lower left. A) 5.1-m footrope; B) 9.5-kg tip weight; C) “Ceiling” panel made with 32-mm mesh to limit upwards escapement of off-bottom fishes; D) Five support lines the outermost two of which are top bridles; D1) Top bridle from beam to headrope and upper wing tip; D2) Lower bridle from beam to wingtip weight; E) 20 cm diameter plastic trawl floats; F) 3.1-m beam; G) Additional middle bridle added ahead of beam. The net can be fished with either a string of 10.2-cm disks over a steel chain attached to the footrope in 10 places, or with two sections of 1.9-cm chain attached between the trailing edges of the tipweights and lower wing tips.

The Stauffer trawl is a type of pelagic trawl known as the modified California Department of Fish and Game “Anchovy” Net. It is also commonly referred to as the NMFS Modified Cobb Trawl.

Both nets are versions of small four-panel pelagic trawl. These trawls consist of four identical panels sewn together along nylon rope riblines. They are designed to be fished midwater to catch schools of small fish and invertebrates.

The Stauffer trawl has a 124 ft. headrope and footrope.

The Shrimp trawl has a 61 ft. headrope and footrope.

The SBE 39plus is a high-accuracy, fast-sampling temperature (pressure optional) recorder with com port interface, internal batteries, and memory. The 39plus is designed for moorings or other long-duration, fixed-site deployments, as well as deployments on nets, towed vehicles, or ROVs.

Measurement Range

Temperature -5 to +45 °C

Optional Pressure 0 to 20 / 100 / 350 / 600 / 1000 / 2000/ 3500 / 7000 m

Initial Accuracy

Temperature ± 0.002 (-5 to +35 °C); ± 0.01 (+35 to +45 °C)

Optional Pressure ± 0.1% of full scale range

Typical Stability

Temperature 0.0002 °C per month

Optional Pressure 0.05% of full scale range per year

Resolution

Temperature 0.0001 °C

Optional Pressure 0.002% of full scale range

Supplemental Information - Sampling Scales and Rates - Descriptive Information about the sampling spatial and temporal scales and rates.

Supplemental Information - Error Analysis - Descriptive Information about the error analysis.

Supplemental Information - Provenance and Historical References -

Descriptive Information about the provenance, historical data, key information packaged elsewhere.

Midwater trawling:

Wilson, M. T. 2000. Effects of year and region on the abundance and size of age-0 walleye pollock, Theragra chalcogramma,

in the western Gulf of Alaska, 1985-1988. Fish. Bull. 98:823-834.

Beam trawling:

Cooper, D.W., J.T. Duffy-Anderson, B.L. Norcross, B. Holladay and P.J. Stabeno (2014). Nursery areas of juvenile northern rock sole (Lepidopsetta polyxystra) in the eastern Bering Sea in relation to hydrography and thermal regimes. ICES J. Mar. Sci, doi:10.1093/icesjms/fst210

There are no legal restrictions on access to the data. They reside in public domain and can be freely distributed.

TBD

User must read and fully comprehend the metadata prior to use. Applications or inferences derived from the data should be carefully considered for accuracy. Data will reside at the Alaska Fisheries Science Center.

Acknowledgement of NOAA/NMFS/AFSC, as the source from which these data were obtained in any publications and/or other representations of these, data is suggested.

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Oracle database and ArcServer user interface.

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Not processed automatically.

No archive currently supports these kinds of data.

local and offsite backups

Descriptive Information about the methods used.

Bering Sea cruises:

Fish were collected using a 3.05-m plumb staff beam trawl with 7-mm mesh and 4-mm codend liner (after Gunderson and Ellis, 1986). Towing speed was 0.5 m s21 (1.0 knot) in 2003, and 1 m s21 in 2008 and 2010.

In 2003 and 2010, total length (TL) of northern rock sole was recorded to the nearest mm. In 2008, northern rock sole were measured to standard length (SL) if ,80 mm SL and to TL if .80 mm SL. Standard lengths were converted to total lengths using conversion

factors developed by measuring both standard and total length of frozen northern rock sole. For fish ,40 mm SL, the conversion factor was TL ¼ 1.2044(SL) + 0.0415, r2 ¼ 0.95, n ¼ 120; and for fish .40 mm SL, the conversion factor was TL ¼ 1.231(SL) –

1.325, r2 ¼ 0.99, n ¼ 106. In all years, subsamples of at least 25 fish were measured if a size class of fish contained too many individuals to measure in the available time.

Gulf of Alaska cruises

Midwater trawl

The Stauffer (a.k.a., anchovy) trawl was deployed to a depth of 200 meters, or 10 meters, off the bottom, whichever is shallowest. Net depth was monitored using the ship’s Simrad ITI (trawl eye) or FURUNO system.

Walleye pollock (all age classes), Pacific cod, capelin, eulachon, and flatfishes were sorted from the catch. It was sometimes necessary to sort walleye pollock into ca. <120 mm SL and ca. >12 cm FL to ensure adequate representation of age-0 and age-1+ components, respectively, in the catch and length data. Flatfishes were sorted to species. For each of these groups, all individuals or a randomly drawn subsample of all individuals was used to determine length composition. For walleye pollock, approximately 100 age-0 and 100 age-1+ walleye pollock were measured for body length. Standard length (SL) is the body-length metric for age-0 walleye pollock. Fork length (FL) is the body-length metric for age-1+ walleye pollock. Subsampling may have been necessary prior to enumerating and measuring individuals. A sample of each of the following groups were frozen for subsequent examination in the laboratory: age-0 walleye pollock, age-0 Pacific cod, age-0 and age-1 yellowfin sole, and each of the other flatfish species (age-0 only). These were flash frozen in the –80 oC freezer and then moved to the –20 oC freezer.

3-m Beam Trawl

A modified plumb-staff, 3-m beam trawl was deployed to collect juvenile flatfishes from the seafloor. Flatfishes, Pacific cod and walleye pollock were the priority for catch processing, other fishes were sorted to the finest taxonomic level practical and then will be enumerated and weighed and the discarded (but see Special Projects). None of the invertebrate portion of the catch was quantified. Flatfish juveniles, walleye pollock, and Pacific cod were sorted to species, then counted, weighed, and lengthed. If catch of any one target species is very high (more than 50 individuals of one species), a subsample was taken for counting and weighing, and the remainder of the sample was weighed and frozen or discarded. After counting and weighing, the fish (age-0 walleye pollock, age-0 Pacific cod, age-0 and age-1 yellowfin sole, and age-0 individuals of all other flatfish species) were put into individual freezer bags (1 bag per species) and put in the -80 C freezer in the rough lab.