Dataset: inshore_trawl stations

Two surveys were conducted; one in the fall beginning October 30, 2000 and a second in the spring, beginning on April 23, 2001. Each cruise required 25 days over a period of five weeks. . Descriptive data, including geo-references, trawl duration, depth, salinity and temperature for each survey are presented. Obviously, a single year of data affords no ability to develop a time series to be used for more than anything but the most general of conclusions. Also, since this was the first year, the first few weeks of the fall survey, especially, was a period in which the crew was testing and developing skills, procedures, and methods. Nevertheless, data collected from this first year does reveal some interesting findings. Ninety-nine taxonomic groups of fish and invertebrates were caught. For this report, we have selected examples for which we can report results. The complete catch result summaries are presented by species for each stratum. Fall 2000 Summary Seventy eight of the 96 planned tows were made. Untowable bottom and presence of fixed gear prevented us from towing the 18 not towed. The volume of the total mixed catch varied from a minimum of 4 kg to a maximum of 640 kg per tow. The average weight of catch was about 122 kg per tow. The total number of species caught in the fall was 80 with a low of 7 and high of 31 in any particular tow. Relative coastwide ranking for the top 10 species is reported below in descending order.

* Species managed by the New England Fisheries Management Council

Species managed by the New England Fisheries Management Council Spring 2001 One hundred eleven tows were made in the spring. We were able to achieve this by anticipating untowable bottom and planning 1 extra randomly selected alternate tow per stratum for a total of 115 planned tows. Weight of total mixed catch varied from a minimum of 4.5 kg to a maximum of 5,007 kg per tow, with an average of 87 kg per tow. Number of species caught per tow ranged from 4 to 31. Total number of species caught during the Spring 2001 survey was 87. Relative coastwide ranking for the top 10 species is reported below in descending order.

* Species managed by the New England Fisheries Management Council.

With 61 finfish species and 38 types of invertebrates sampled, a species by species presentation of results is not practical for this report. However, following are some examples of the sorts of results that this survey can produce. Note that we include some examples of non-groundfish species to demonstrate another attribute of a fisheries independent survey; that the survey can provide information beneficial for management of the system and not focus soley on a select suite of target species. Information is gathered on an ecological community level. Rainbow smelt, for example, may not be directly exploited commercially but it provides enjoyment to upland recreational anglers and on an ecological level is a forage species for higher trophic levels. Sculpins, cartilaginous species, and predator-prey ratios, for example, have been used as indicators of system-wide health. Landings data do not include information on these species. Over the long term, system shifts as a result of climate change may be assessed as exemplified when the Fall Survey encountered species such as barracudina and scup that historically have not been common north of Cape Ann, Massachusetts. By looking at population structure as well as distribution, the importance of shallow inshore habitat for cod becomes clear. The Fall 2000 portion of Figure 8 shows a year class of cod that probably hatched in February-April 1999. Most are still in the shallowest strata. As the fish grow, they move offshore and disperse into deeper water. In the Spring 2001 portion of Figure 8, one can see young of the year in the shallow strata. Offshore in the spring, there appears to be more cod in the deeper strata but certainly not in the numbers that were observed the previous fall. From a single year’s tow, it is not possible to know whether or not the spring survey missed the next year class due to late inshore migration or whether there simply was a weak year class. Cod, and most other groundfish species, move into deeper (warmer) water in late fall to return in the spring as inshore waters warm. Whether the fish were still farther offshore and had not migrated in at the time of the spring survey, we cannot determine. The spring of 2001 was cooler than normal. Subsequent year’s tows and comparisons with the offshore NMFS data set will help to resolve this question. As the Maine spring spawning closure for groundfish 'sunsets' at the end of 2002, trawl survey data will be used to evaluate the need to extend the closure during the next Maine legislative session.