Chesapeake Bay Fishery- Independent Multispecies Survey (CHESFIMS) T. J. Miller 1, C. J. Heyer 1, E. D. Houde 1,A. F. Sharov 2, B. Muffley 2, M. C. Christman 3, N. Herman 3, J. H. Volstad 4 and K. Curti 1 1. CBL UMCES Solomons, MD Biometry Program UMCP College Park, MD Fisheries Service MDNR Annapolis, MD Versar Corp Columbia, MD 21405

Background q The STAC workshop on Multispecies management (Houde et al., 1998) concluded multispecies approaches to Chesapeake bay fisheries are desirable. q Chesapeake 2000 commits to: 1By 2005, develop ecosystem-based management plans for targeted species. 1By 2007, revise and implement existing FMPs to incorporate ecological, social and economic considerations, multispecies fisheries management and ecosystem approaches.

Toward ecosystem-based management q “There is no substitute for good monitoring programs of fished species and of key interacting species. Modeling evolves from and depends on monitoring results, and management depends upon an understanding of the status and trends of stocks. Fishery-independent surveys to monitor resources and obtain biological data, if instituted and coordinated throughout the bay, would help improve management.” Executive summary of Multispecies Management workshop report. Houde et al. 1998

Chesapeake Bay Fish Population ?

Characteristics of a fishery- independent survey q A baywide multispecies survey must: 1Adequately sample the pelagic, benthic and nearshore habitats used by the fish communities in Chesapeake bay. 1Accurately estimate relative (or absolute) abundance for key species. 1Provide recruitment indices for key species. 1Provide biological characteristics of key species including: 1Age- and size-structure. 1Diet data by age- and size-class. 1Integrate with existing fishery-independent surveys.

CHESFIMS q 3 components 1Baywide, broadscale midwater trawl survey. 1Stratified random sample involving two-stage stratification (regions: upper, mid, lower, and transects within regions). 1Samples depths > 5m, using an 18 m 2 -midwater trawl (6 mm cod end) fished in 10 equal depth bins from surface to bottom. 1Builds on existing 1995 – 2000 NSF-sponsored survey (TIES). 1Regional, shoal survey. 1Stratified random sample currently involving 4 strata. 1Samples depths < 5m, using a 16’ otter trawl towed for 6 min. 1Complements and extends existing MDNR and VIMS surveys. 1Statistical evaluation. 1Analysis of alternative survey designs to optimize final survey design. 1Application of spatial statistical models as to develop Baywide abundances.

Broadscale surveys q 3 surveys 1Spring 14/30 – 5/5/ stations 11,473 fish (~ 67 kg) 1Summer 17/16 – 7/23/ stations 181,630 fish (~127 kg) 1Autumn 19/25 – 9/29/ stations* 173,619 fish (~76 kg) Upper Mid Lower

Shoal survey q Spring 15/11 – 6/6/ stations fish q Summer 17/10 – 8/6/ stations 18,755 fish q Autumn 19/24 –10/16/ stations 14,627 fish S1 S2 S3 S4 Solomons Surveys conducted in four mid-Bay strata, chosen for compatibility with broadscale efforts, and with existing surveys

Summary catch results Broadscale Shoal SpringSummerAutumn

Species diversity

Distribution of Diversity Shannon-Weiner Diversity Index SpringSummerAutumn

Broadscale catch summaries

Shoal catch summaries

Analysis of abundance q Produce robust estimates of relative abundance of fish in aggregated categories (e.g.., piscivores, benthic, estuarine- dependent, etc.). q Produce robust estimates of relative abundance of individual species using standard survey approaches. q Produce robust estimates of recruitment levels of individual species. q Map the distribution of key species, by life stage and habitat. q Conduct gear comparison tows to allow comparison of shoal and broadscale data. q Using spatial statistical approaches to produce robust estimates of integrated baywide abundance.

Abundance trends

TIES heritage bay anchovy striped bass alosids menhaden weakfish spot others white perch croaker 1995 bay anchovy striped bass alosids menhaden weakfish spot others white perch croaker 1996 bay anchovy alosids menhaden weakfish spot others striped bass croaker white perch 1997 bay anchovy striped bass alosids menhaden weakfish spot others croaker white perch 1998 bay anchovy weakfish spot others white perch menhaden alosids striped bass croaker 1999 bay anchovy striped bass alosids menhaden weakfish spot others white perch croaker 2000

Distribution of abundance Bay anchovy SpringSummerAutumn Catch.tow -1

Biological characteristics q Both shoal survey (shown right) and broadscale survey can provide data on: 1Size and size-at-age 1Recruitment 1Habitat associations q For a wide range of species Hogchoker

Diet summaries q Gut contents flushed, sample split, taxa identified, weighed and counted. q Spring cruise. 175% of sampled fishes processed to remove guts. 163% of sampled fishes processed for gut contents. q Summer cruise. 111% of sampled fishes processed to remove guts. 11% of sampled fishes processed for gut contents. q Autumn cruise 1To be processed

Sample diets

Statistical evaluation q Comparison of alternative effort allocation 1Design factors calculated for alternative analysis q Survey performance evaluation underway using measurements of precision q Analysis of alternative tow lengths in shoals data underway q Development of spatial modeling

Progress and plans q Completed 3 broadscale and 3 shoal survey cruises in q Analysis of abundance data nearing completion. q Analysis of biological characteristics of catch nearing completion. q Analysis of dietary data underway. q Statistical evaluation involving alternative sampling strategies and spatial statistical approaches underway. q Broadscale and shoal survey dates selected for 2002 with expanded coverage.