T/. , I I . a I a'jtee. ANNUAL REPOI-1T 2002 'N.N;1Itp, "I.- I - , "-, ' - O'Drizzly,- - . ;-" 7 I .':I- - 11' iJ Monitoring the Marine Environment of Long Island Sound at Millstone Power Station Milsoe n ir o.mental ,' . v. M~illstone En}vironmnental Laboratory- 101.trnfi 2003 j. Monitoring the Marine Environment of Long Island Sound at * Millstone Power Station 20 Au Report 2002 Annual Report Prepared by: Staff of Millstone Environmental Laboratory Millstone Power Station Dominion Resources Services, Inc. ,- . , . I Approved by: -"v =, /Zt.x, A_ Dr. Milan Keser April 2003 Acknowledgements i This report was prepared by the personnel of Dominion Resources Services, Inc. Environmental Laboratory, located at Millstone Nuclear Power Station, PO Box 128, Waterford, CT 06385. Staff members in 2002 included: t Dr. Milan Keser, Supervisor Donald J. Danila Gregory C. Decker David G. Dodge James F. Foertch Raymond 0. Heller Donald F. Landers, Jr. { Douglas E. Morgan Dr. Edward F. Roseman John T. Swenarton Christine A. Tomichek Joseph M. Vozarik Thanks are also given to the summer intern staff from the University of Connecticut and Connecticut College for their considerable efforts in the field and laboratory: Chris Blair, Christine Culver, Larissa Graham, Jakub Kircun, Sean LaBrie, Kristen Thibodeau, and Tara Wyatt. Dr. Victor Crecco, Penelope Howell, and David Molnar of the Connecticut Department of Environmental Protection, Fisheries Division; David Taylor of the University of Rhode Island, Graduate School of Oceanography; Thomas Currier of the Massachusetts Division of Marine -J Fisheries; Tim Lynch of the Rhode Island Department of Envirornental Management, Division of Fish and Wildlife; and Dr. Michael Scherer of Marine Research, Inc. kindly supplied information on finfishes and lobster used in this report. Critical reviews of this report and oversight of the monitoring programs were completed by Dr. Ernesto Lorda, consultant to Millstone Environmental Laboratory, and the following members of the Millstone Ecological Advisory Committee: Dr. John Tietjen (chair; emeritus, City University of New York), Dr. W. Huntting Howell (University of New Hampshire), Dr. Nelson Marshall (emeritus, University of Rhode Island), Dr. William Pearcy (emeritus, Oregon State University), Dr. Saul Saila (emeritus, University of Rhode Island), Dr. Robert Whitlatch (University of Connecticut), and Dr. Robert Wilce (emeritus, University of Massachusetts). ii Monitoring Studies, 2002 I Table of Contents Acknowledgements ............ ....... ii Executive Summary................................................................................................................................ v Introduction.............................................................................................................................................1 Winter Flounder Studies .................. 9 Fish Ecology Studies .................. 129 Lobster Studies .................... 173 Rocky Intertidal Studies .................... 203 Benthic Infauna ................... 237 elgrass .. .................. 269 Table of Contents iii iv Monitoring Studies, 2002 Executive Summary Winter Flounder Studies comparison to the long-term (1983-2002) time-series in both Niantic River and Bay. However, more Stage The local Niantic River population of winter floun- 1 larvae were found than expected from the relatively der (Pseudoplezfronectes aniericanus) is potentially low spawner abundance. This was attributed to high- affected by the operation of Millstone Power Station er egg survival, a potentially important compensatory (MPS), particularly by entrainment of larvae through mechanism. Overall, larval winter flounder 'abun- the cooling-water systems of the operating units. As dance in 2002 was below average in the Niantic River a result, extensive studies of the life history and and was the third lowest in 20 years in Niantic Bay. population dynamics of this important sport and Rates of larval growth and development were posi- commercial species have been undertaken since 1976. tively correlated with water temperature, but 'other Each year, surveys of adult spawners are carried out factors such as density and prey abundance'likely also in the Niantic River during late winter and early affected growth. Despite relatively high water spring. Larval sampling is conducted at the plant dis- temperatures, growth rate of larvae this year in both charges, in Niantic Bay, and at three stations in the the river and bay were the lowest of their respective Niantic River. Age-0 juveniles are collected at two time-series. This may have affected survival as the sites in the river. Winter flounder are also commonly larval mortality rate in 2002 increased from record found in year-round trawl monitoring program (TMP) low levels during the past 2 years to just below the samples. long-term average. Density-dependence was exam- Seawater temperature, which can have potentially ined by comparing mortality and-egg production important effects during spawning, egg incubation, estimates (a measure of yolk-sac larval stage abun- the larval period, and the remainder of the first year dance) at* various monthly and seasonal water of life, attained record or near-record highs during temperatures. Results of this analysis suggested that most months of 2002. During the 2002 adult winter larval mortality decreased with decreasing egg flounder spawning season, A-mean trawl catch-per- production (i.e., density-dependency) and increasing unit-effort (CPUE) of fish larger than 15 cm in the April water temperatures (i.e., faster development).' Niantic River was 2.2. Although relatively low, this Following larval metamorphosis and settlement, CPUE represented about a 50% increase over 2001. demersal age-0 young were sampled by beam trawl at Abundance of winter flounder spawners peaked in the two sites in the Niantic River. 'Following a record early, 1980s and decreased thereafter, most likely high abundance of newly settled young in 2001, from stock and recruitment effects (i.e., decreased densities were lower this year, although better than per-capita recruitment at high stock sizes), a generally those typically observed since 1983. Mortality rate in warming winter trend, and increased, rates of 2002 was about the same as the long-term average at exploitation. Niantic River CPUE was significantly one station, but was the third highest at the other correlated with several other winter flounder abun- station. Although sampling variability was relatively dance indices in other Southern New England waters high in 2002, juvenile abundance in late summer and numbers currently remain low throughout the appeared to be lower than during the past 2 years. region. The 2001-02 A-mean CPUE calculated for young The Jolly stochastic model was applied to mark and winter flounder'collected during late fall and early recapture data to estimate the absolute abundance of winter at TMP stations was the lowest recorded in 26 the Niantic River adult spawning population. The years and did not reflect the high abundance of the abundance estimate for 2001 of winter flounder larger 2001 year-class as indicated by beam trawl sampling than 20 cm was 4.1 thousand, the lowest estimate of during the previous summer. Nevertheless, over the the series. Other recent estimates of about 6-10 long term these two age-0 abundance indices were, thousand fish were considerably. less than estimated significantly correlated ' and helped to 'identify population sizes during 1984-91, which ranged emerging strong or weak year-classes. In any case, between about 33 and 80 thousand. Annual female however, fewer'age-I juveniles have been taken spawner abundance estimates since 1976 ranged from during each year of the Niantic River adult spawning 2 thousand in 2001 ;to 75 thousand in 1982, with population surveys since the early 1980s, with a' corresponding total egg production estimates from CPUE for fish in the lower river navigational channel about 1.7 to 44.8 billion for the same years. particularly low. This abundance decrease was much Abundance of newly-hatched (Stage I) winter less when a CPUE was calculated for fish found only flounder larvae was about average this year in in the upper portion of the river. The distribution of Executive Summary v age-I fish in Niantic River and Bay appeared to have Empirical mass-balance calculations showed that a changed over the years, which was attributed to large number of entrained larvae likely come from a environmental factors (e.g., water temperature, number of sources in Long Island Sound (LIS), I bottom habitat) unrelated to MPS operation. including stocks associated with the Connecticut and Abundance indices of age-0 young were either not Thames Rivers, as well as from the Niantic River. significantly correlated or were negatively correlated For the second year, estimates of the fraction of with the abundance of female adult spawners 3 to 5 entrained larvae in 2002 from the Niantic River were 1I years later. Conversely, positive correlations were similar when determined by either the mass-balance 4 found between age-I abundance indices and these model (14%) or an independently conducted study of older fish. However, the forns of these significant genetic stock identification (12%). Remarkably simi- 1 lar estimates in both 2001 and 2002 suggested that relationships were unclear. Thus, none of the early I life stages were considered to be a reliable predictor the mass-balance model provided reasonable esti- of potential