Full report - Conservation Gateway

Chapter 2 - Coastal EcosystemsLacking other spatial data sources for these species, musselscould therefore not be included in ecoregional abundancemapping.For managed species, more than 50% of areas in the regionincluded data for populations of Eastern oyster, hard clam,softshell clam, and bay scallop. For these species, most ofthe “Not Reported” areas appeared to be in states withoutsubstantial natural populations remaining. For example,oysters were under-reported in most of Maine and NewJersey; hard clams were under-reported in Maine andsouth of Virginia; and softshell clams and bay scallopswere not reported south of New Jersey. In addition tospecies absence, some under-reporting was likely due toinconsistencies among states. NOAA noted that “dataquality was directly related to the resources available toconduct shellfish management responsibilities.” However,state managers did provide “final verification of the datacontent” (NOAA 1997). With a greater than 50% overallreporting rate, very good coverage of state-managedshellfish beds, and few other reporting options, the CSAdatabase was determined to be a reasonable and adequatesource for regional shellfish reporting.In developing a map of target shellfish distribution andabundance, CSA entries with ranked abundances forthe four target species under state management (oyster,hard clam, softshell clam, and bay scallop) were used.Abundance ranks could not be compared across states andfurther do not provide any historical context for shellfishdistribution and abundance. Therefore, ranks of “High,”“Medium,” and “Low Abundance” for each shellfish specieswere converted to present and ranks of “None” or“Not Reported” to absent. In addition, each area was assigneda number from 0 to 4 depending on the number ofreported target species present there in order to identifythose areas of particular importance for protection ofshellfish assemblages.Eastern oyster, hard clam, softshell clam, and bay scalloplandings data were queried for each state for the entirereporting period of the database (1950 to 2007). Data arefrom continuous records collected by joint state and federalagencies, and reported as metric tons (wet weight).To understand the changes in historical landings for eachstate and species, time series of annual landings were analyzedfor 1) maximum annual harvest in the series, 2) yearof the maximum harvest, 3) total number of years reported(out of 58 possible reporting years from 1950 to 2007),4) mean value for the last three years reported in the timeseries, and 5) last three-year average as a percentage ofthe maximum annual harvest. New Hampshire, as theonly assessment state without commercial shellfish landings,was not included in the NMFS database. For NewHampshire, a time series of annual estimates of standingstock was analyzed for Eastern oyster and softshell clam,as surveyed by the New Hampshire Department of Fishand Game (NHEP 2006). Results are presented inTable 2-4.Several important caveats apply to this use of commerciallandings data as a proxy for abundance. First, data are notnormalized for fishing effort. Peak harvest benchmarksmay reflect levels of unsustainable pressure. Further, it ispossible to have a sustainable fishery even if current harvestlevels are very low compared to historic benchmarks.Natural variability in year-to-year recruitment can alsoproduce wide swings in standing stock and harvest opportunity.Finally, NMFS mollusk datasets include aquaculturelandings (totals not available separately) that contributeto recent landings totals and may mean that the resultspresented here overestimate natural bed conditions. Forthe four target species, maps were developed to show thelast 3-yr average landings as a percent of maximum harvestby 0 - 10%, 11 - 50%, and 51 - 100% levels for each state(Figure 2-9, 2-10, 2-11, and 2-12).Population StatusAs a proxy for population status, National MarineFisheries Service (NMFS) monthly commercial landingsdata were analyzed for mollusk species (NOAA 2008).2-26Northwest Atlantic Marine Ecoregional Assessment • Phase 1 Report