Overview of Selected Bottom Trawl Survey Data 1948-1962

Linda I. Despres
Carlos A. Castro
Heather L. Sagar
Gina Reppucci

January 1999

List of Contents


1.0 Background

2.0 Data Format

2.1 Changes to Station Data

2.2 Changes to Catch Data

3.0 Literature Cited

List of Tables:


Table 1. Selected Bottom Trawl Surveys 1948-1962

Table 2. Data Form Field Comparison: 1948-1949 vs. Current

Table 3. Data Form Field Comparison: 1950-1955 vs. Current

Table 4. Data Form Field Comparison: 1956 vs. Current

Table 5. Updated Species Common Names

Cruise 102

Species and Length Frequency Occurrence Index
Station-Stratum-Tow Index
Stratum-Tow-Station Index

Cruise 105

Species and Length Frequency Occurrence Index
Station-Stratum-Tow Index
Stratum-Tow-Station Index

Cruise 112

Species and Length Frequency Occurrence Index
Station-Stratum-Tow Index
Stratum-Tow-Station Index

Cruise 119

Species and Length Frequency Occurrence Index
Station-Stratum-Tow Index
Stratum-Tow-Station Index

Cruise 126

Species and Length Frequency Occurrence Index
Station-Stratum-Tow Index
Stratum-Tow-Station Index

Cruise 133

Species and Length Frequency Occurrence Index
Station-Stratum-Tow Index
Stratum-Tow-Station Index

Cruise 137

Species and Length Frequency Occurrence Index
Station-Stratum-Tow Index
Stratum-Tow-Station Index

Cruise 156

Species and Length Frequency Occurrence Index
Station-Stratum-Tow Index
Stratum-Tow-Station Index

Cruise 162

Species and Length Frequency Occurrence Index
Station-Stratum-Tow Index
Stratum-Tow-Station Index

Cruise 165

Species and Length Frequency Occurrence Index
Station-Stratum-Tow Index
Stratum-Tow-Station Index

Cruise 181

Species and Length Frequency Occurrence Index
Station-Stratum-Tow Index
Stratum-Tow-Station Index

Cruise 212

Species and Length Frequency Occurrence Index
Station-Stratum-Tow Index
Stratum-Tow-Station Index

Cruise 312

Species and Length Frequency Occurrence Index
Station-Stratum-Tow Index
Stratum-Tow-Station Index

1.0 BACKGROUND


Bottom trawl data collections began with the R/V Albatross I as far back as the late 1800s. However, the first attempt to collect data systematically was made by the Fish and Wildlife Service, predecessor of the National Marine Fisheries Service (NMFS), in 1948, with the R/V Albatross III. Even though the data were not consistently collected in a standard format, they are good indicators of the status of the resources, especially on Georges Bank, prior to the intensive foreign and domestic fishing efforts of the early 1960s. In order to preserve and utilize this historical information, the Resources Surveys Branch began to process, convert and enter selected bottom trawl cruise data from 1948-1962 using current standards (Table 1, Selected Bottom Trawl Surveys 1948-1962). The objective of this effort is to make this information available in a relational database structure for scientists and interested individuals in the user community. These data are contained within the NEFSC database, in three standard tables: station, catch, and length, and can only be released in summary format by contacting the Resource Surveys Branch staff.


A similar report entitled "A Synopsis of Groundfish Survey Cruises (Albatross III, Delaware) 1948-1962" was prepared in 1976 by Overholtz and Montiero. We have introduced fundamental format changes and corrections to the original version. The information contained in this document was gathered from bottom trawl logs, sailing orders, cruise reports, cruise tracks, and personal communications with retired NMFS scientists.


The 1948-1962 historical bottom trawl sampling designs concentrated in areas where commercially valuable species, particularly haddock, were abundant. Two sampling schemes defined this era: random selection of stations, stratified by depth (1948-1951) and non-random stations, spaced at regular intervals, organized in transects and grid patterns, (1952-1962). The random scheme concentrated primarily on Georges Bank with sporadic sampling of the Gulf in Maine and Southern New England. Stations were placed in 7 x 10 mile rectangles and distributed in three depth zones: 0-55, 56-110, and greater than 110 meters. The non-random scheme expanded the sampling areas to include more of the Gulf of Maine and Browns Bank (Overholtz and Montiero, 1976).


Table 1. Selected Bottom Trawl Surveys 1948-1962

Computer
Code
Vessel Cruise # Season Date Year Area Stations Tow
Duration (min.)
Depth Range
(m)
RPM Gear used Sampling
Design
# 105 Albatross III 5, 6, 7, 9 Summer 7/13-9/10 1948 Georges Bank - South Channel 138 23-70 33-229 180-220 1.5 Iceland Random
112 Albatross III 10,11,12,14 Fall 9/29-12/9 1948 Gulf of Maine - S. New England 101 18-195 26-229 200 1.5 Iceland Random
126 Albatross III 26, 27, 28 Summer 7/27-9/16 1949 Gulf of Maine - S. New England 193 2-40 26-263 200 1.5 Iceland Random
133 Albatross III 33, 34, 35 Spring 3/15-5/11 1950 Nova Scotia - S. New England 196 20-60 25-311 135-210 1.5 Iceland Random
137 Albatross III 37, 38 Summer 7/6-8/3 1950 Browns Bank - S. New England 202 13-66 24-311 200-210 1.5 Iceland Random
102 Delaware 2, 3 Spring 8/14-9/4 1951 Georges Bank 107 2-50 27-225 Not recorded 1.5 Iceland Random
% 156 Albatross III 56 Winter 1/28-2/11 1955 Georges Bank 52 20-30 38-223 200-225 Yankee 36 Non-random
% 162 Albatross III 62 Spring 6/6-6/18 1955 Georges - Brown's Bank 91 20-32 24-293 200-215 Yankee 36 Non-random
165 Albatross III 65, 66 Fall 9/8-9/28 1955 Browns Bank - S. New England 138 10-35 17-322 Not recorded Yankee 36 Non-random
181 Albatross III 81, 82 Fall 11/2-11/21 1956 Browns Bank - S. New England 95 15-47 20-340 210 Yankee 36 Non-random
%*119 Albatross III 18,19,20 Fall 9/22-10/17 1958 Gulf of Maine-S. New England 140 2-35 22-283 110-220 Yankee 36 Non-random
212 Delaware 12,13 Fall 9/23-10/27 1959 Browns Bank - S. New England 157 1-51 6-307 210 Yankee 36 Non-random

312
Delaware











419

Delaware












512

Delaware












#        Crew of cruise # 9 operated between 7:15 PM to 6:05 AM
%      Stations were pre-numbered but not occupied in sequential order. Two teams of scientists worked a six hour watch, twice a day.
*      Crunum was originally composed of three digits; due to character limitations they were shorted to two digits. The first three digits of the station number corresponds to the original station number; the fourth digit indicates the tow number. The log for station 0011 is missing. Station 0221, 0231, 0251, 1111 and 1121 were not occupied.

2.0 DATA FORMAT


In 1948, station, catch and oceanographic data contained on the trawl logs were not recorded in the same format as they are today. The process of standardizing this information required a variety of format changes and required careful manual auditing. In order to convert these historical data and to document changes over time, we created a series of Data Field Comparison charts (Tables 2, 3, and 4) accompanied by scanned images of the Historical Trawl Logs (Figures 1, 2, and 3).


Most of the selected cruises had one to three copies of the trawl logs and sometimes we found discrepancies between the originals and the second or third copies. We consistently used the information on the original trawl logs as the true copy; all corrections were made to the original version of the trawl logs.


2.1 CHANGES TO STATION DATA


During this period, a unique cruise number was assigned each time a vessel departed from its home port, even though it may have been conducting several parts of a single type of survey (e.g., cruise 5, 6, 7 and 9 were part of a single bottom trawl survey). Currently, a computer code number combines multiple parts of a survey into one cruise. Another difference is that from 1948-1955, each cruise started with station number 1 and each station may have had one or two tows associated with it. We renumbered each station by maintaining the original "station" number and combining it with the original "tow" number. For example, if the trawl log indicated station 1, tow 1, the new station number became 0101. In addition, we assigned a "stratum-tow" number based on the station's position (latitude and longitude). This procedure essentially post-stratified these historical data and made them compatible with our current data structure.


Numerical values for station type, relative success of the haul, and gear condition (SHG) have also been added to the trawl log and the database (see selected cruises for Station-Stratum-Tow Index and Stratum-Tow-Station Index). Specific depths were not consistently indicated; in instances where depth ranges were recorded, we entered the average depth as the start depth of the tow. In addition, we did not audit the field "Cable" since the cable out to depth ratio was never defined.


We determined the statistical area of each station by using the station's position and the Standard New England Statistical Area Code for commercial data. Vessel operations were normally conducted 24 hours per day. From 1948-1951, the 1.5 Iceland Trawl was used with rollers, with and without a Vigneron-Dahl and with a liner in the codend and belly (Knake, 1963). From 1955-1962, a #36 Yankee Trawl was used with rollers and liner ( and inch) in the codend and belly.


We converted all pertinent fields from the English to the metric system and from Fahrenheit to Celsius degrees. We also converted wind direction, weather, wind speed, and wave height to a numerical value using the Beaufort scale. Because tow duration was not specified on the logs, we calculated this value by using the time difference between the start and the end of the tow.


Bottom and surface temperatures were often corrected on the hydrographic logs after the completion of the cruise with more precise data obtained from post-processed bathythermo-graphic slides. We also incorporated these corrected values onto the original trawl logs.


Table 2. DATA FORM FIELD COMPARISON: 1948-1949 vs. CURRENT
Albatross III, Cruise # 5, 6, 7, 9, 10, 11, 12, 14, 26, 27, 28

HISTORICAL FIELD NAME(1) CURRENT FIELD NAME FIELD DESCRIPTION
Cruise # Cruise # Assigned vessel cruise number
Station # Station# Sequential number which is not repeated. Station# and tow# were combined to form a new station #.
Tow # Tow # Indicates the number of tows conducted within the stratum
Date Date Actual date. The order was change from day/month to month/day
Subarea Does not exist
Course Course Actual course of the vessel recorded in compass degrees
Tow hour on bottom Time Local time using the 24- hour clock. Midnight hour = 0000
Tow hour off bottom Towdur Actual time out for gear. Calculated by subtracting the time of the beginning and the end of the tow
On deck Does not exist
Distance thru water Doppler water Distance traveled in nautical miles while doppler tracking in water mode
Distance over bottom Doppler bottom Distance traveled in nautical miles while doppler tracking in bottom mode
Wire out Cable Cable in water measured in meters from the water surface to the bottom. Converted from fm to m
Speed thru water DesSpeed Designated towing speed for a particular gear
Speed over bottom Does not exist
RPM RPM Average revolution per minute while under tow
Gear Gear Type Specific gear type used during survey
Remarks Does not exist
Position Beglat, beglong; endlat, endlong Beginning and ending latitude and longitude
Biologist on duty Watch Chief
Depth Setdepth Depth at the end of the tow. Converted from fm to m
Bottom Does not exist
BT # XBT Indicates the type of equipment used to obtain temperature data
Nansen # Other gear Code for other gear used during the survey
Salinity Does not exist
Tmp (btm) Bottemp Bottom temperature. Converted from F to C degrees
Wind direction Windir Wind direction. Converted from alphabetical to numerical values
Wind force Windsp Speed in knots. Converted from Beaufort scale to speed in knots
Current Dir Does not exist
Current force Does not exist
Weather Weather Converted from weather description to weather code
Sea Wave hgt Height of waves to 0.1 m. Converted from Douglas Scale to m

Note: The following fields were added to the historical form:
SHG = station type (S), haul type (H), and gear condition (G)
Statistical Area = the standard New England statistical area code for commercial data
Strata = areas of a particular range of depths. Usually separated into 2 categories: inshore and offshore
Total # species = the total number of species captured at one station
Total # of length frequency sheets = refers to the number of length frequency pages attached to the trawl log of one particular station

1. To obtain specific information about field descriptions in the historical format, refer to the 1948 Manual of Instructions for Scientists

Figure 1. Historical Trawl Log from 1948-1949


Table 3. DATA FORM FIELD COMPARISON: 1950-55 vs. CURRENT
Albatross III, Cruise # 33, 34, 35, 37, 38, 56, 62, 65, 66
Delaware, Cruise # 2, 3

HISTORICAL FIELD NAME(1) CURRENT FIELD NAME FIELD DESCRIPTION
Cruise # Cruise # Assigned vessel cruise number
Station # Station# Sequential number which is not repeated. Station# and tow# were combined to form a new station #.
Tow # Tow # Indicates the number of tows conducted within the stratum
Date Date Actual date. The order was change from day/month to month/day
Subarea Does not exist
Unit Area Does not exist
Tow hour hooked up Time Local time using the 24- hour clock. Midnight hour = 0000
Tow hour start back Towdur Actual time out for gear. Calculated by subtracting the time of the beginning and the end of the tow
Course Course Actual course of the vessel recorded in compass degrees
Distance thru water Doppler water Distance traveled in nautical miles while doppler tracking in water mode
Distance over bottom Doppler bottom Distance traveled in nautical miles while doppler tracking in bottom mode
Wire out Cable Cable in water measured in meters from the water surface to the bottom. Converted from fm to m
Speed thru water DesSpeed Designated towing speed for a particular gear
Speed over bottom Does not exist
RPM RPM Average revolution per minute while under tow
Gear Gear Type Specific gear type used during survey
Remarks Does not exist
Position Beglat, beglong; endlat, endlong Beginning and ending latitude and longitude
Loran Loran 1, Loran 2 Position Indicator. Originally recorded as Loran A
Depth Setdepth Depth at the end of the tow. Converted from fm to m
Bottom Does not exist
BT # XBT Indicates the type of equipment used to obtain temperature data
Nansen # Other gear Code for other gear used during the survey
Salinity Does not exist
Temp (btm) Bottemp Bottom temperature. Converted from F to C degrees
Wind direction Windir Wind direction. Converted from alphabetical to numerical values
Wind force Windsp Speed in knots. Converted from Beaufort scale to speed in knots
Current Dir Does not exist
Current force Does not exist
Weather Weather Converted from weather description to weather code
Sea Wave hgt Height of waves to 0.1 m. Converted from Douglas Scale to m

Note: The following fields were added to the historical form:
SHG = station type (S), haul type (H), and gear condition (G)
Statistical Area = the standard New England statistical area code for commercial data
Strata = areas of a particular range of depths. Usually separated into 2 categories: inshore and offshore
Total # species = the total number of species captured at one station
Total # of length frequency sheets = refers to the number of length frequency pages attached to the trawl log of one particular station

1. To obtain specific information about field descriptions in the historical format, refer to the 1948 Manual of Instructions for Scientists

Figure 2. Historical Trawl Log from 1950-1955

Table 4. DATA FORM FIELD COMPARISON: 1956 vs. CURRENT
Albatross III, Cruise #18, 19, 20, 81, 82 Delaware #12,13

HISTORICAL FIELD NAME(1) CURRENT FIELD NAME FIELD DESCRIPTION
Cruise # Cruise # Assigned vessel cruise number
Station # Station# Sequential number which is not repeated. Station# and tow# were combined to form a new station #.
Tow # Tow # Indicates the number of tows conducted within the stratum
Date Date Actual date. The order was change from day/month to month/day
Subarea Does not exist
Unit Area Does not exist
Hour hooked up Time Local time using the 24- hour clock. Midnight hour = 0000
Start back Towdur Actual time out for gear. Calculated by subtracting the time of the beginning and the end of the tow
Course Course Actual course of the vessel recorded in compass degrees
Distance thru water Doppler water Distance traveled in nautical miles while doppler tracking in water mode
Distance over bottom Does bottom Distance traveled in nautical miles while doppler tracking in bottom mode
Wire out Cable Cable in water measured in meters from the water surface to the bottom. Converted from fm to m
Speed thru water DesSpeed Designated towing speed for a particular gear
Speed over bottom Does not exist
RPM RPM Average revolution per minute while under tow
Gear Gear Type Specific gear type used during survey
Remarks Does not exist
Position Beglat, beglong; endlat, endlong Beginning and ending latitude and longitude
Loran Loran 1, Loran 2 Position Indicator. Originally recorded as Loran A
Depth Setdepth Depth at the end of the tow. Converted from fm to m
Bottom type Does not exist Temperature data recorded
BT # XBT Indicates the type of equipment used to obtain temperature data
Samples Does not exist
Temperature surface Surftemp Surface temperature. Converted from F to C degrees
Temperature bottom Bottemp Bottom temperature. Converted from F to C degrees
Wind direction Windir Wind direction. Converted from alphabetical to numerical values
Wind force Windsp Speed in knots. Converted from Beaufort scale to speed in knots
Current Dir Does not exist
Current force Does not exist
Weather Weather Converted from weather description to weather code
Sea Wave hgt Height of waves to 0.1 m. Converted from Douglas Scale to m


Note: The following fields were added to the historical form:
SHG = station type (S), haul type (H), and gear condition (G)
Statistical Area = the standard New England statistical area code for commercial data
Strata = areas of a particular range of depths. Usually separated in 2 categories: inshore and offshore
Total # species = the total number of species captured at one station
Total # of length frequency sheets = refers to the number of length frequency pages attached to the trawl log of one particular station

1. To obtain specific information about field descriptions in the historical format, refer to the 1948 Manual of Instructions for Scientists

Figure 3. Historical Trawl Log from 1956



2.2 CHANGES TO CATCH DATA


Bottom trawl surveys from 1948-1962 provided a significant volume of data for several commercially important finfish species such as haddock, cod, silver hake, and flounders. Personal conversations with former NMFS staff indicate that during the early days of the surveys three teams of two scientists worked a four hour watch, twice a day (unless otherwise noted). Due to this schedule, fishermen played a significant role in helping scientists to separate and identify the catch. It is possible that some species were misidentified but we did not alter the original species identification data nor did we include the number of the fish seen "floating out of the net" as recorded in the remarks section.

We also updated selected vernacular names used at the time with common names currently in use (Table 5, Updated Species Common Names). We have transcribed total numbers or volume (e.g., "bushels of scallops" or "quarts of squids") of a species captured at any given station onto the trawl log from either the "remarks" or "catch" section, or from the backside of the trawl log or separate length frequency sheet. Species with less commercial value (e.g., skates, grenadiers, sculpins, sea raven, octopus, shrimp) often lacked length frequency data or were recorded inconsistently. Additionally, young-of-year and "mashed fish" are included as part of the total catch, but, some of their length frequencies are missing.

To provide specific species information for every cruise, we have listed a summary of the total number of species captured per station and total number of stations with recorded length frequency (refer to the Species and Length Frequency Occurrence Tables for specific cruise information). Occasionally, additional miscellaneous information was added as a footnote in some of the tables.

In some instances, lengths were recorded in ranges (e.g., "5 haddock between 25-30 cm"); this information was entered into a "comments" field. Fish were measured in centimeters and rounded down to the nearest whole centimeter (refer to Manual of Instructions for Scientists for further details). Lobsters were originally measured in inches (using a ruler) from the eye socket to the end of the carapace; we converted these readings to millimeters. Only crabs and flounders identified to species were entered into the database. If several species of shrimp were recorded on the trawl log, we coded them as shrimp unclassified; total numbers of shrimp were not entered as is the current practice.


The original data did not include calculated expansion factors; we calculated them by dividing the total catch number by the total subsample number. We have also corrected errors on the trawl logs when species length frequency totals were erroneously tabulated.


Table 5. UPDATED SPECIES COMMON NAMES

Historical species common names used from 1948-1962 and their current common name equivalent.

Key Historical Common Name Current Common Name Species Code
* big skate winter skate 023

blackback winter flounder 106
* black hake offshore hake 069

blennies combtooth blennies 733
* brier skate clearnose skate 024
* brown shark sandbar shark 009

catfish wolffish 192

cat shark chain dogfish shark 014
* common skate little skate 026

cusk eel cusk eel uncl. 461

cuttlefish bobtail squid uncl. 506

dab American plaice 102

daylight windowpane 108

deep sea gurnard flying gurnard 175
* deep sea puffer smooth puffer 195

deep sea robin armored sea robin 173
X deep sea sculpin sculpin uncl. 160

deep sea smelt Atlantic argentine 046
* eel pout ocean pout 193
* frogfish Atlantic batfish 199

gar Atlantic needlefish 471

gar Flat needlefish 068
* grey sole witch flounder 107
* grubby sculpin little sculpin 116

hake uncl. Urophycis uncl. 087

herring Atlantic herring 032

kingfish (locate position), northern 146

kingfish (locate position), southern 652

lemon sole winter flounder 106

mailed sculpin moustache sculpin 161
* marlin spike common grenadier 091

mud hake white hake 076

octopus octopus uncl. 510
@ prickly skate skate uncl. 020

rattail grenadier uncl. 090

red sea robin armored sea robin 173

rock cod Atlantic cod 073

rockling four-beard rockling 083
* rosefish redfish 155
* sand dab windowpane 108

sculpin longhorn sculpin 163
* sea bass black sea bass 141

sea herring Atlantic herring 032

sea perch Serranidae 554

sea robin northern sea robin 171

shrimp shrimp uncl. 305

skate skate uncl. 020
# smelt herring Atlantic argentine 046

smooth shark smooth dogfish 013

sorrel rough scad 212

spiny skate thorny skate 028

squeteague weakfish 145
+ squid squid uncl. 501
* squirrel hake red hake 077
X starry skate thorny skate 028

swellfish northern puffer 196

toadfish oyster toadfish 185

triggerfish triggerfish uncl. 820

whiting silver hake 072

KEY:

*       Verified in the 1971 NMFS Resource Surveys Branch species code list.

X       Verified in Bigelow and Welsh, Fishes of the Gulf of Maine, Washington Government Printing Office, Washington,1925.

#       Verified in Bigelow and Schroeder, Fishes of the Gulf of Maine , United States Government Printing Office, Washington, 1953.

+       Loligo and Illex were not sorted into separate species, therefore; they are coded as squid unclassified.

@       Due to taxonomic changes that occurred between Bigelow and Welsh, 1925, and Bigelow and Schroeder, 1953, prickly skates have been coded as skate unclassified. Personal communications with George Kelly, former NMFS fisheries biologist, Jon Moore, taxonomist, presently working as a visiting scientist at the NEFSC-NMFS, Woods Hole, MA., and Karsten Hartel, curator, Museum of Comparative Zoology, Harvard University, MA, confirmed that this species was often misclassified.


LITERATURE CITED


Knake, Boris O. 1956. Assembly Methods for Otter Trawl Nets. U. S. Dept of Interior, Fish and Wildlife Serv., Bureau of Comm. Fish., Fish Leaflet 437; 30p.


Overholtz, W. and E. Montiero. 1976. A Synopsis of Groundfish Survey Cruises (Albatross III, Delaware I) 1948-1962. Woods Hole Lab. Ref. Doc. 76-13; 24p. Available from: National Marine Fisheries Service, Woods Hole, MA.


ACKNOWLEDGMENTS


For anecdotal, programming, and support assistance, we would like to generously thank the following past and present NMFS employees:

www.nefsc.noaa.gov
NMFS Search
Link Disclaimer
webMASTER
Privacy Policy
(File Modified Nov. 26 2004)