Gulf of Maine-Georges Bank Ichthyoplankton 
Collected on ICNAF Larval Herring Surveys 
September 1971-February 1975 
JOHN B. COLTON, JR. and RUTH R. BYRON! 
ABSTRACT 
The families, genera, and species of all larval fishes are tabulated and the abundance, length 
frequencies, and distribution of 12 species and 2 families are summarized utilizing data collected on 8 
ichthyoplankton surveys of the Gulf of Maine-Georges Bank area. The segregation of coastal and 
oceanic species north and south of the coastal/slope water boundary during December is evidenced in 
a comparison of the distribution of upper 100-m integrated temperature and Atlantic herring, Myc- 
tophidae, and Paralepididae larvae. All larval barracudinas and lanternfishes occurred in areas 
where the integrated temperature was above 11° and 13°C, respectively. Ninety-one percent of 
positive larval herring tows were in areas where the integrated temperature was below 13°C. 
INTRODUCTION 
In 1971 the International Commission for the North- 
west Atlantic Fisheries (ICNAF) inaugurated a series of 
cooperative surveys of larval Atlantic herring, Clupea 
harengus harengus L., in the Gulf of Maine-Georges 
Bank area. The objectives of these surveys were to 
delimit the major herring spawning grounds and to ob- 
tain relative estimates of spawning stock size and infor- 
mation on larval drift and dispersal (International Com- 
mission for the Northwest Atlantic Fisheries 1971, 1972). 
These surveys, incorporating standardized sampling 
methods and stations, have been continued annually 
since inception. Vessels from six countries have par- 
ticipated, and 28 full-scale surveys have been completed 
as of June 1976. In addition, a number of supplementary 
coastal cruises of more limited scope have been under- 
taken in connection with this study. 
In this paper we present summaries of the abundance, 
length frequencies, and distribution of the more abun- 
dant larval fishes collected on eight cruises by U.S. ves- 
sels from September 1971 to February 1975. The data 
were based on 61-cm, 0.505 mm-mesh bongo net samples 
collected on the following cruises: 
No. 
Cruise No Date stations 
Delaware IT 71-4 22 Sept.-3 Oct. 1971 122 
Albatross IV 71-7 3-17 Dec. 1971 148 
Albatross IV 72-9 28 Nov.-15 Dec. 1972 127 
Albatross IV 73-9 4-20 Dec. 1973 113 
Albatross IV 74-2 11-22 Feb. 1974 56 
Delaware II 74-12 8-12 Oct. 1974 56 
Albatross IV 74-13 4-18 Dec. 1974 108 
Albatross IV 75-2 15-28 Feb. 1975 87 
‘Northeast Fisheries Center, Narragansett Laboratory, National Mar- 
ine Fisheries Service, NOAA, Narragansett, RI 02882. 
FIELD AND LABORATORY METHODS 
Stations were made sequentially on a standardized 
grid pattern (International Commission for the North- 
west Atlantic Fisheries 1972). At each station a 3.5-knot 
(6.5-km/h), double-oblique tow was made using paired 
61-cm bongo samplers (Posgay and Marak in press) fit- 
ted with 0.505-mm and 0.333-mm nylon mesh nets. The 
sampler accessories (flowmeter, time-depth recorder, 
towing wire, and wire depressor) were rigged from 
specifications described by Posgay and Marak (in press). 
On Delaware II Cruise 71-4, the maximum depth of tow 
was 200 m or approximately 5 m off the bottom. The net 
was deployed at 50 m/min and retrieved at 20 m/min to 
40-m depth. The upper 40 m of the water column was 
sampled in 20, 2-m intertal steps of 1-min duration. On 
Albatross IV Cruise 71-7 the sampling procedure was 
similar except that the net was retrieved continuously at 
10 m/min from 40 m to the surface. On all other cruises 
the maximum depth of tow was 100 m or approximately 5 
m off the bottom, and the net was deployed at 50 m/min 
and retrieved at 10 m/min. Pertinent station data for the 
eight cruises are listed in Tables 3-10. 
All samples were processed at the Northeast Fisheries 
Center, Narragansett Laboratory, National Marine 
Fisheries Service, NOAA. Fish larvae were sorted from 
the total 0.505-mm mesh samples and the larvae from 
each sample enumerated by species or to the lowest taxa 
possible. For samples having less than 100 of a species, 
all larvae were measured to the nearest 0.1-mm standard 
length. The larvae were later combined into 1-mm and 3- 
mm size groups. In samples containing more than 100 
larvae of a species, a subsample of at least 100 specimens 
was taken for length measurements and the total length 
frequency for that species determined by multiplying the 
number at each length interval by the reciprocal of the 
aliquot fraction. 
