Source: RUTGERS, THE STATE UNIVERSITY OF NEW JERSEY submitted to NRP
RAISING SURF CLAMS IN NEW JERSEY
Sponsoring Institution
National Institute of Food and Agriculture
Project Status
COMPLETE
Funding Source
Reporting Frequency
Annual
Accession No.
0187590
Grant No.
(N/A)
Cumulative Award Amt.
(N/A)
Proposal No.
(N/A)
Multistate No.
(N/A)
Project Start Date
Dec 1, 2000
Project End Date
Sep 30, 2005
Grant Year
(N/A)
Program Code
[(N/A)]- (N/A)
Recipient Organization
RUTGERS, THE STATE UNIVERSITY OF NEW JERSEY
3 RUTGERS PLZA
NEW BRUNSWICK,NJ 08901-8559
Performing Department
INST OF MARINE & COASTAL SCI
Non Technical Summary
Aquaculture techniques for surf clams will be optimized to the New Jersey environment with particular emphasis on development off shore aquaculture.
Animal Health Component
100%
Research Effort Categories
Basic
(N/A)
Applied
100%
Developmental
(N/A)
Classification

Knowledge Area (KA)Subject of Investigation (SOI)Field of Science (FOS)Percent
30837241050100%
Goals / Objectives
Objectives are: 1)to further refine hatchery techniques for conditioning and rearing surf clams out of season; 2) to optimize growth in upwellers to minimize nursery time; 3) to determine whether off-bottom farming techniques can be used instead of bottom culture; and 4) to determine if the offshore environment can be successfully used as an aquaculture site.
Project Methods
Hatchery and nursery techniques will be optimized with respect to food supply, larval or seed density, and food/habitat quality. Grow-out will test the use of long-line technology offshore of central New Jersey at the LEO site. Long line protocols will be optimized with respect to planting density, seed size used and vertical position of the suspended arrays in the water column. Comparison will be made to a high salonity leased ground near Ocean City where standard on-bottom culture techniques will be used.

Progress 12/01/00 to 09/30/05

Outputs
The purpose of this project was to (a) determine the viability of surf clam aquaculture and (b) develop information on the health of the surf clam stock off the coast of New Jersey. In 2001, surf clam (Spisula solidissima)culture was initiated to augment the half-shell and steamed clam trade. Trial grow-out studies have shown that Spisula can be grown to marketable size (50-55 mm) in one year. This can be facilitated by spawning from the fall through early spring to have clam seed ready for grow-out through the entire growing season. This results in the early availability of surf clam seed, which can be moved into our nursery facility by late winter or early spring in any given year. Growth rates were rapid enough to provide marketable animals in less than two years. Results of the aquaculture component showed that fouling of shells was the greatest impediment to commercialization. Growth rates and survival were adequate even during relatively warm summers. The second component of the project initiated two critical studies on the health of surf clam stocks. In 2003, a histopathological survey of surf clams was conducted to identify the reasons for unexpectedly high surf clam mortalities off southern New Jersey and Delmarva The most northern stations had the highest condition indices, the lowest gonadal abnormality scores, with one exception, and the lowest digestive gland atrophy scores. Animals at the stations with lowest average condition index had body weights less than 65% of the average animal taken at the station with the highest condition index. A syndrome describing a malnourished state common in clams taken along the mortality line emerged from this analysis. Animals with low condition were also animals with higher scores of gonadal abnormality and digestive gland atrophy. Starvation, brought on by regional shifts in temperature mismatching food supply and feeding rate with tissue maintenance needs, offers one potential mechanism explaining the distribution of apparently-malnourished clams and the origin of the increase in mortality nearshore along the Delmarva and southern New Jersey coast. In 2004, a survey of surf clam condition was conducted to further investigate the impact of increased mortality due to global warming on surf clam stock abundance and health. A total of 242 stations were visited from Chesapeake Bay to Hudson Canyon. Condition index was highest inshore, with the exception of a few of the most inshore stations, and lowest at the offshore edge of the clam's range. An estimate of meat weight for a standard 120-mm clam, from site-specific length-weight regressions, revealed that the animals near the center of the inshore-offshore distribution had a greater weight for a given length than those living at the edges of the clam's range, probably due to the influence of temperature on feeding and growth. Low condition in the extreme inshore locations suggests that warmer temperatures continue to negatively affect surf clam nutrition and indicate the continued susceptibility of clams along the southern and inshore boundary to warming in the Mid-Atlantic Bight.

Impacts
The Hatch project has fostered improved management of the surf clam resource. Accomplishments include the following. 1. A successful hatchery technology has been developed to rear surf clams to seed size 2. A successful grow-out technology has been developed to rear surf clams to 'little-neck' size. 3. A histopathology survey has demonstrated malnourishment accompanying increased water temperatures as the dominant reason for mortality along he southern boundary of the surf clam stock's range. 4. A histopathology survey has ruled out parasitism and disease as a major source of mortality. 5. A survey of condition index has shown that the surf clam stock continues to be susceptible to global warming at both the northern and southern boundaries of the range, where clams in poor condition dominate the population.

Publications

  • Weinberg, J.R., E.N. Powell, C. Pickett, V.A. Nordahl, Jr. and L.D. Jacobson. 2005. Results from the 2004 cooperative survey of Atlantic surfclams. Northeast Fish. Sci. Center Ref. Doc. 05-01:1-41.


Progress 01/01/04 to 12/31/04

Outputs
Rutgers University participated in an emergency surf clam survey coordinated with the NMFS and the surf clam industry to investigate the impact of increased mortality due to global warming on surf clam stock abundance and health. Clam samples were collected by the F/V Lisa Kim, homeport Point Pleasant, New Jersey, between June 26 and July 6, 2004. The cruise covered inshore and offshore stations from Hudson Canyon to near North Carolina. A total of 242 stations were visited, the surf clams caught counted and measured and a total of 1,835 clams selected for follow-up assessment of condition index. Selected animals were opened by cutting both adductor muscles using a stainless steel knife. Each opened animal was then rinsed in a series of sea water buckets to remove sand and other hard particles forced into the mantle cavity during capture, drained, placed in a small Zip-lock bag, and stored in freezers until processing. In the laboratory, frozen animals were placed in a cold room to be defrosted a day before processing. Each individual sample bag was opened and liquid inside the bag was transferred to a plastic weighing dish. The defrosted animals were then shucked with a stainless steel knife and meat was placed into the same plastic weighing dish to get a wet weight. The maximum anterior-posterior shell length of each animal was measured with a caliper. The liquid and meat were put on a sieve to drain extra liquid, blotted on a paper towel,and reweighed to get a blotted wet weight. The meat was minced and placed in a drying oven set at 90 C for 3 days, then weighed to obtain a dry weight. Results of analyses will be provided to the NMFS and the surf clam industry at a March retrospective and planning meeting for the 2005 field effort.

Impacts
The clam industry and NMFS, in cooperation with Rutgers University, will incorporate the information into the 2005 surf clam stock assessment. A planning meeting will be held in March with field work expected to commence in June and ending in Sepember. It is anticipated that this field work will include a larger histopathology program , dredge calibration studies, and a full stock survey and will ultimately lead to an updated stock assessment. The project also emphasizes the serious issues facing New Jersey fisheries and aquaculture with respect to global warming.

Publications

  • Kim, Y. and E.N. Powell. 2004. Surfclam histopathology survey along the Delmarva mortality line. J. Shellfish Res. 23:429-441.


Progress 01/01/03 to 12/31/03

Outputs
The 2002 NMFS-NEFSC survey revealed a substantial reduction in the abundance of surf clams, Spisula solidissima, off the Delmarva Peninsula. Increased mortality since 1999 was focused inshore of a southeast trending line extending from approximately the Delaware Bay mouth to the central continental shelf off the mouth of Chesapeake Bay.To further investigate the proximate causes of mortality, we carried out an histopathological survey of surf clams collected along this southeast-trending `mortality' line. The most northern stations had the highest condition indices, the lowest gonadal abnormality scores, with one exception, and the lowest digestive gland atrophy scores. Animals at the stations with lowest average condition index had body weights less than 65% of the mean animal taken at the station with the highest condition index. Large reductions in condition index indicate malnutrition. Additional evidence of malnutrition accrues from the tendency for stations yielding clams in lowest condition to also yield clams with above normal scores for abnormal gonadal development and high scores for digestive gland atrophy. A syndrome describing a malnourished state common in clams taken along the mortality line emerges from this analysis. Animals with low condition are also animals with higher scores of gonadal abnormality and higher scores of digestive gland atrophy. Neither parasites, nematodes and cestodes occurred commonly in tissue sections, nor inflammatory responses, likewise common,were significantly correlated with low condition index and the associated tissue disorders. Nematodes, and the frequently associated focal inflammatory response, were not obviously more common in the southern stations where condition index was low. Cestodes tended to be more common at sites where condition index was low, but infection intensity was high at stations not so characterized. No disease-causing organisms were observed in this study. Starvation brought on by regional shifts in temperature mismatching food supply, feeding rate, and tissue maintenance offers one potential mechanism explaining the distribution of apparently-malnourished clams and the origin of the increase in mortality inshore of the `mortality' line.

Impacts
The clam industry and NMFS, in cooperation with Rutgers University, will incorporate the information into the 2004 industry-funded surf clam science program. A planning meeting will be held on February 10 with field work expected to commence in June. It is anticipated that this field work will include a larger histopathology program , including sampling in New Jersey waters, and will ultimately lead to a refinement of the stock assessment program. The project also emphasizes the serious issues facing New Jersey fisheries and aquaculture with respect to global warming.

Publications

  • No publications reported this period


Progress 01/01/02 to 12/31/02

Outputs
Surf clam (Spisula solidissima) culture at HSRL was initiated to produce a substitute for imported ``Manila''-type clams, and also augment the half-shell and steamed clam trade, currently dominated by the hard clam (Mercenaria mercenaria). With growth rates twice that of hard clams, surf clams hold exceptional aquacultural promise. Our trial grow-out studies have shown that Spisula can be grown to marketable size (50-55 mm) in one year. This can be facilitated by spawning from the fall through early spring to have clam seed ready for grow-out through the entire growing season. This results in the early availability of surf clam seed, which can be moved into our nursery facility by late winter or early spring in any given year. An experimental lease was obtained in lower Delaware Bay to test clam grow-out techniques. The largest clams from the fall of 2001 continued growing throughout the unusually mild winter of 2001-2002. Throughout the spring of 2002, smaller clams from the previous season were sorted and placed in cages for deployment on our leases. The rapid growth of the clams and the severe fouling of our gear far exceeded our ability to keep up with the required maintenance of these clams. As a result, even though growth was excellent, many cages became overcrowded and/or buried in sediment resulting in large mortalities which are still being assessed. About half of the cages have been returned to Cape May Harbor, where easier access will permit reorganization over the winter of 2002-2003. The rest remain on our Delaware Bay leases as we arrange for a larger vessel with greater capacity to aid in their recovery. In the meantime, we have acquired more seed for next season from a commercial hatchery in Maine, and we are preparing to spawn our own seed late this winter. Our nursery system continues to improve and our clam seed production methods have become very reliable. A revised lease deployment strategy is being developed to avoid the problems of the past year, and despite a current lack of marketable clams, market interest remains high.

Impacts
With growth rates twice that of hard clams, surf clams hold exceptional aquacultural promise.

Publications

  • No publications reported this period


Progress 01/01/01 to 12/31/01

Outputs
Surf clam (Spisula solidissima)culture at HSRL was initiated to produce a substitute for imported ``Manila''-type clams, and also augment the half-shell and steamed clam trade, currently dominated by the hard clam (Mercenaria mercenaria). With growth rates twice that of hard clams, surf clams hold exceptional aquacultural promise. Our trial grow-out studies have shown that Spisula can be grown to marketable size (50-55 mm) in one year. This can be facilitated by spawning from the fall through early spring to have clam seed ready for grow-out through the entire growing season. This results in the early availability of surf clam seed, which can be moved into our nursery facility by late winter or early spring in any given year. Two major surf clam spawns were performed during the past year. The first spawn, during the fall, demonstrated that large-scale production of surf clam seed was possible. The second spawn took place during the spring and succeeded to the point where our hatchery capacity was exceeded. This success further confirms our ability to produce large numbers of surf clam seed. In 1999, surf clam seed that were put into our grow-out facility in April at a shell length of 2-3 mm had reached a shell length of 45 mm by November. The 2000 and 2001 growing seasons were used to improve hatchery output and grow-out survival and growth. To date, survival through the grow-out system has increased 10-fold, from 1-2% in 1999 to over 20% in 2001. This translates into approximately 200,000 surf clams on hand at the end of the 2001 growing season. A small percentage of these clams were of marketable size, but the majority required more growth. Early this year, a new upweller site was established at 2-Mile Landing in Cape May County. This site is being improved to serve as the main nursery site for surf clams. This spring, an experimental lease was obtained in lower Delaware Bay to test clam grow-out techniques. To this end, about 50,000 clams were moved onto this lease. These clams have shown continued growth and excellent survival into the winter. They should be ready for market in the spring of 2002.

Impacts
(N/A)

Publications

  • No publications reported this period