IV.E.7. Impacts on Commercial and Sport Fisheries

Impacts on commercial and sport fishing will come primarily from oil spills, chronic discharges, and spatial exclusion of fishing by rigs, platforms, and gas pipelines. The following analysis addresses each of these topics and then aggregates their total effect.

Commercial Fisheries - Offshore Oil Spills

Even though Nelson-Smith (1972) suggested that actively swimming adult finfish tend to avoid areas of contamination, this type of behavior does not seem to be universal with all fish and lifestages, as experiments with juvenile English sole seem to indicate (Weber et al., 1979). An oil spill that occurs in Mid-Atlantic offshore waters can be expected to contact eggs and/or larvae of commercially important fish and shellfish suspended in the upper water layers, no matter what time of year the spill occurs. Oil spill impacts are more serious for early life stages because the toxicity threshold is lower, and the eggs, and to some extent the larvae, are unable to avoid oiled waters. After investigating oil induced egg and larvae mortalities, Longwell1 (1977) concluded that natural genetic selection would result in populations with resistance against particular pollutants. However, resiliency can be exhausted. "An exploited species of fish might be expected to be less resilient than a whole ecosystem. In the same manner, a commercial fishery would be less resilient than a natural population" (Longwell, 1977).

Prediction of the effects of offshore oil spills is subjective, at best. The magnitude of impact on the resources in question is determined by the exact combination of biological, physical, chemical, and, in the case of commercial fisheries, economic parameters at the time of spill occurrence. These results vary widely. The assertion that early life stage mortalities play a large part in determining impacts on commercial fish stocks has been suggested by some researchers. Hennemuth et al. (1980) reviewed several commercial fisheries with extensive data collected over many years. This study concluded that "Comparison of recruitment estimates and associated catches over time (years) indicated that significant deviations in catch closely followed significant deviations in recruitment." Also, Teal and Howarth (1984) concluded that "Although adult fish can be killed by oil spills, this probably poses less of a threat to commercial fisheries than does damage to eggs and larvae, or changes in the ecosystem supporting the fishery." It would appear that a large part of the natural fluctuation in fish populations is primarily the result of variation in mortality during the first year of life. However, this natural variability in fish stocks, resulting from strong periodic year classes, makes the assessment of oil-induced impacts very difficult. A poor year class could be the result of an oil spill, other pollution event, or the less than optimum combination of ecological conditions for the individual year of consideration. Teal and Howarth (1984) summarized observed impacts on shellfish and finfish as a result of the Florida, Arrow, Argo Merchant, Bravo, Tsesis, Amoco Cadiz, and IXTOC I offshore oil spills. These data are presented in Table IV.E.7-1, and show the variability of observed impacts.

In order to evaluate the effects of an offshore oil spill on commercial fisheries, several modelling approaches have been investigated URI and ASA, Inc. (1982) looked at potential impacts on Georges Bank stocks of cod and herring. This study concluded that the species-specific compensatory behavior was important in determining recovery of commercial fish stocks. Of the two

Table IV.E.7-1. Observed effects of oil spills on fish and fisheries.

species investigated, cumulative losses to the herring fishery were projected to be relatively greater than those of cod, as a result of the greater compensatory ability of the cod species. Figure 43 (Appendix G) shows the compensatory reaction of cod stocks modelled. Cod impacts were again modelled by Reed et al. (1980). In this study an oil spill of 10 million gallons from a tanker released uniformly over a 36-hr period was simulated. The magnitude of impacts on cod were estimated to range between 0 and 10 percent of the annual maximum sustainable yield of approximately 25,000 metric tons, or up to $2.5 million (in 1979 dollars). Cross et al. (1984) performed some calculations of potential impacts on the menhaden fishery off North Carolina. This simulation concluded that total biomass would be reduced by about 12 percent over 30 years relative to the initial level. All these modelling efforts use inputs which tend to approximate some of the most serious spill conditions for the species of investigation. They set contact times for seasons of peak vulnerability, and release large quantities of oil in areas where eggs and larvae concentrate. Actual effects of an offshore oil spill could be as simulated, or less, depending upon the spill conditions and ecological variables.

Tables IV.E.6-1, and B-1 through B-3 (OSRAM, Appendix C), list the conditional probabilities of contact for important nearshore areas as well as offshore locations where shelf spawning is known to occur. Many of the top ten mid-Atlantic commercial fisheries (Table III.C.3-1) are distributed primarily in bays, estuaries, and coastal waters. Important shellfish resources such as blue crab, surf clam, hard clam, bay scallop, and oyster are found almost exclusively within State waters. Probabilities of contact to coastal segments and bays from an assumed spill of >1,000 bbl which occurs within the proposed sale area indicates that spilled oil trajectories are generally not shoreward. Oil spills modelled within the Sale area do not show extremely vast movement. It would appear that the chances of an oil spill contacting important bays and shellfish beds in the mid-Atlantic are remote.

As Figure 41 (Appendix G) shows, the continental shelf waters of the midAtlantic are important areas of spawning activity. Commercially important mid-Atlantic species that spawn in shelf waters include sea scallop, squid, scup, ocean quahog, black seabass, bluefish, and summer flounder. As calculated in Section IV.E.6, the probability of an oil spill of >1,000 bbl that occurs within the sale area entering shelf waters less than 200 m in depth is approximately 47 percent. This estimation is for the time period of 3 days after spill occurrence, and represents the period of greatest toxicity. If such a spill were to occur during spring or summer, initial egg and larvae mortalities could result. The effect this would have on the commercial stocks affected would be difficult to determine, but couild reduce recruitment if stocks were already declining.

The implications of these oil spill trajectory analyses to mid-Atlantic fishery resources is that species generating eggs and larvae in coastal and nearshore waters are not likely to experience oil spill induced mortalities if a spill were to occur from within the proposed sale area. Species generating pelagic eggs and/or larvae distributed over the continental shelf may be subjected to initial egg and larvae mortalities. The magnitude of the oil-induced impacts on these fisheries is dependent upon the complex interaction of the biological, chemical and physical variables at the exact time of spill occurrence. For the two species of concern profiled in Section III.C.3; tilefish and striped bass,

the implications are slightly different. Striped bass, a coastal and estuarine species with anadromous spawning, is not likely to experience egg and larvae mortalities from OCS spilled oil. Conversely, tilefish could be affected if a spill occurred during the peak spawning season of May to October (see Section III.C.3). However, tilefish are known to be fractional spawners, and could compensate for one-time losses easier than an annual spawner.

Chronic Impacts

Habitual discharges of drilling muds and cuttings, formation waters and other incidental contaminants described in Section III.A.5 are anticipated to occur as a result of exploration and development activity. Studies conducted and/or summarized by several researches such as NRC (1983), SAI (1982), Bothner et al. (1983), and Battelle New England Marine Research Laboratory and WHOI (1983), indicate that potential impacts on fishery resources from chronic discharges are quite low. This is especially true in the mid-Atlantic where the majority of the commercially valuable finfish and shellfish occur in inshore waters.

Pipeline Placement

It is projected that over the 30-year life span of the field for Sale No. 111, there will be a total of 200 miles of gathering pipeline and 100 miles of trunkline (mean case scenario). Both trunk and connecting lines will be used for gas reserves only. It is projected that only one pipeline will be necessary, but could come ashore at either Sea Girt (NJ) or Bethany Beach (DE), depending upon discovery location.

Pipelines placed in coastal waters may be buried to prevent physical disturbance from storms and/or reduce potential gear conflicts with commercial fishermen. Burial of pipelines results in resuspension of sediments in a localized area. This type of activity can be expected to produce localized impacts on commercially valuable populations of blue crab, ocean quahog, sea scallop, and surf clams found in the vicinity of both proposed pipeline routes. Impacts associated with pipeline placement where trenching is required include direct burial of benthic species, increased turbidity which produces abrasion and fouling, local changes in water quality such as suspension of organic materials and heavy metals, and local declines in dissolved oxygen levels. While these effects can be locally significant, these impacts are not expected to affect the regional populations of mid-Atlantic shellfish which have a wide distribution and could easily compensate for local disturbances. Impacts from pipeline placement are expected to be short-term, localized and moderated by current dispersal. Localized demersal fishery resources such as crabs and shellfish may be affected during pipeline placement, but repopulation from adjacent areas is expected, with little discernable impact above natural fluctuations occurring to any of these resources.

Catch-Loss Model

Estimates of the economic impacts on commercial fishing in the mid-Atlantic resulting from spatial preclusion of fishing activity because of rig and pipeline placement are calculated using the model developed for Sale No. 59 (Centaur Associates Inc., 1981). Landing inputs were updated to reflect 1981 values. Distances of buffer zones that fishermen would avoid (assumed for the model) were 0.5 miles for drilling rigs and platforms (this includes 0.25 miles for the actual buffer zone and 0.5 miles for the extent of an anchoring system

or satellite subsea completion) and 0.25 miles for pipelines. Even though calculated dollar losses are shown to the nearest dollar, these values are estimated, and should not be construed as absolute. Figure IV.E.7-1 summarizes these data for all the fishing industries analyzed.

Figure IV.E.7-1.

Summation of the economic losses resulting from spatial
preclusion of the mid-Atlantic sea scallop, surf clam,
ocean quahog, lobster (otter trawl), and groundfish
(otter trawl) fisheries.

As can be seen from Figure IV.E.7-1, the fishery affected to the greatest extent is the sea scallop fishery. It is estimated that approximately $8,000 would be lost annually from 1996 on because of spatial preclusion of fishing activity. However, this amount represents less than one percent of the value of the mid-Atlantic sea scallop fishery in 1982 and far less than the $5,017,000 fluctuation in the value of sea scallop landings between 1981 and 1982.

Fishing Ports

Two potential locations have been identified as possible support bases for OCS activities in the mid-Atlantic. They are Davisville, Rhode Island and the Norfolk, Virginia area. Marine services required by OCS service vessels can be very similar to those required by commercial fishermen. The amount of fishing activity carried out from Davisville is quite limited. Of the twenty berthing spaces available to fishing vessels only approximately half