by Jason McNamee, Supervising Marine Biologist, RIDFW
The year 2012 marked the 26th year for the Narragansett Bay Juvenile Finfish survey. This survey is one of the major projects conducted annually by the RIDEM – Division of Fish and Wildlife Marine Section. The survey consists of sampling eighteen stations around Narragansett Bay (see Figure 1) once a month from June through October with a 61m X 3.05m beach seine deployed from a boat. Individuals of all finfish species are quantified for length and number. Species of invertebrates are also identified and estimated for abundance. Every effort is made to return all fish and invertebrates to the water alive.
Winter flounder, tautog, bluefish, scup, and members of the clupeid family (menhaden, river herring, sea herring), the target species for this study, are probably the most economically important finfish species in Narragansett Bay. Since the beginning of the Juvenile Finfish Survey in 1986 our understanding of the juvenile life stage of these species has increased substantially. Patterns of spatial and temporal abundance, growth rates, and habitat requirements are better understood today than they were in 1986. Associations with other species and correlations with water quality are emerging. Previous to this study information on juveniles of many recreational and commercially important species in Narragansett Bay was extremely limited. Data collected from each year’s survey provide information on the relative abundance, temporal, and spatial distribution of each species in Narragansett Bay during the survey period. Length frequency data characterizes the juvenile population structure for each species and is used to estimate annual growth rates. Composition of the fish community structure at each station and bay-wide is also characterized. Data analyzed for each year is compared with that from previous years to identify annual variations and population trends. An example of the data collected for tautog is provided in Figure 2. During the normal process of sampling, data on weather and tidal stage are also collected. Measurements of water temperature, salinity and dissolved oxygen are taken close to the bottom with a water quality meter.
The Narragansett Bay Seine survey represents the first comprehensive effort to gather data on juvenile finfish in Narragansett Bay and incorporates these data into species management plans. The data are kept in a large database at the Ft. Wetherill Marine Laboratory. In addition to their use by stock assessment biologists at the R. I. Division of Fish & Wildlife, these data are used by the Atlantic States Marine Fisheries Commission (ASMFC) in developing coast-wide Fisheries Management Plans (FMPs), as well as by the RI Marine Fisheries Council (RIMFC) as they help to develop state specific management plans. The Juvenile Finfish Survey has also been identified as one of the monitoring studies incorporated into the Narragansett Bay Estuary Program’s long term monitoring program. These data have also been used in developing dredging windows and sequencing for a variety of projects in Narragansett Bay. Juvenile finfish and their habitat data have been used for evaluating a myriad of coastal development proposals from outfalls to residential docks to large-scale marinas.
From a fisheries management perspective the importance of long term monitoring of juvenile finfish populations cannot be overemphasized. Juvenile abundance indices are valuable in developing and modifying species management plans. Changes in year class strengths can be monitored, changes in management strategy anticipated, and regulations can be promulgated in advance of a “crisis” situation. With the development of management plans for other species in progress or proposed, these kinds of data sets are becoming more important to fisheries managers, and it is imperative that monitoring studies like this be continued.
Regulations in red are new this year.
Purple text indicates an important note.