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American shad

JOB III. AMERICAN SHAD HATCHERY OPERATIONS, 2006

Abridged report for PFBC website

M.L. Hendricks
Pennsylvania Fish and Boat Commission
Benner Spring Fish Research Station
State College, Pa.


SUMMARY

Five shipments of hickory shad eggs (15 million eggs) were received at Van Dyke in 2006. Egg viability was 61% and 9.2 million hickory shad larvae were stocked in Conowingo Reservoir and in the Delaware River and its tributaries, Pennypack Creek and Ridley Creek.

A total of 46 shipments of American shad eggs (19 million eggs) was received at Van Dyke in 2006. Total egg viability was 35% and survival of viable eggs to stocking was 74%, resulting in production of 4.9 million larvae. Larvae were stocked in the Juniata River (2.7 million), the Susquehanna River near Montgomery Ferry (28 thousand), the West Branch Susquehanna River (315 thousand), the North Branch Susquehanna River in Pennsylvania (274 thousand), Conodoguinet Creek (164 thousand), the Conestoga River (160 thousand), Swatara Creek (135 thousand, West Conewago Creek (135 thousand), the North Branch Susquehanna River in New York (230 thousand) and the Chemung River in New York (172 thousand). Delaware river source larvae were stocked in the Lehigh River (293 thousand), the Schuylkill River (254 thousand) and the Delaware River (53 thousand).

Overall survival of larvae was 74%. No episodes of major mortality occurred as a result of larvae lying on the bottom of the tank but unexplained mortalities occurred in 12 tanks late in the season. Van Dyke jars with foam bottom screens were used seven times with no mortality problems.

All American and hickory shad larvae cultured at Van Dyke were marked by 4-hour immersion in oxytetracycline. Marks for American shad were assigned based on release site and/or egg source river. Mark retention for American shad was 100% for most groups analyzed, however a two groups exhibited less than 100% retention. Hickory shad were marked at 512 ppm on day three. Mark retention for hickory shad was 95%.

INTRODUCTION

The Pennsylvania Fish and Boat Commission has operated the Van Dyke Research Station for Anadromous Fishes since 1976 as part of an effort to restore diadromous fishes to the Susquehanna River Basin. The objectives of the Van Dyke Station were to research culture techniques for American shad and to rear juveniles for release into the Juniata and Susquehanna Rivers. The program goal was to develop a stock of shad imprinted to the Susquehanna drainage, which will subsequently return to the river as spawning adults. With the completion of York Haven Dam fish passage facilities in 2000, upstream hydroelectric project owners were no longer responsible for funding the hatchery effort. Funding was provided by the Pennsylvania Fish and Boat Commission.

In 2003, a new effort in migratory fish restoration was undertaken. Adult hickory shad (Alosa mediocris) were collected and tank-spawned as part of the initial efforts to culture, release and restore runs of hickory shad to the Susquehanna and Delaware River basins.

As is previous years, production goals for American shad for 2006 were to stock 10-20 million American shad larvae. All Van Dyke hatchery-reared American and hickory shad larvae were marked by immersion in tetracycline bath treatments in order to distinguish hatchery-reared shad from those produced by natural spawning of wild adults. All eggs received at Van Dyke were disinfected to prevent the spread of infectious diseases from out-of-basin sources.

EGG SHIPMENTS

Hickory shad

A total of 15.1 million hickory shad eggs (26.8 L) were received in five shipments from tank-spawning operations at Conowingo Dam (Table 1). Some 9.2 million (60.6%) of the hickory shad eggs were viable.

Table 1

 

Table 2

Figure 1

American shad

A total of 19.0 million American shad eggs (394 L) were received in 46 shipments in 2006 (Table 1). This was the fourth lowest quantity of eggs received since 1982 (Tables 2 and 3, Figure 1). Egg collections were reduced, in part, due to cold, wet weather on the Hudson River. Overall American shad egg viability (which we define as the percentage which ultimately hatches) was 35.2%.

Eleven Potomac River egg shipments (4.5 million eggs) were received from April 13 to May 5, 2006. Overall viability was 44.4%. These collections marked the first use of Potomac River eggs for the Susquehanna River restoration since 1974.

Six Hudson River egg shipments (1.9 million eggs) were received from May 9 to May 30, 2006. Overall viability was 68.6%. By comparison, in 2005, 13 shipments were received from the Hudson River for a total of 2.9 million eggs. Hudson River egg shipments have varied without trend from 3 million to over 17 million during 1989 to 2006 (Table 3, Figure 1).

Table 3

Delaware River egg shipments were received from May 8 to June 1. A total of 12 shipments were received (2.3 million eggs) with a viability of 50.0%. By comparison, in 2005, the Delaware River produced 6.2 million eggs. Delaware River egg shipments have declined from approximately 10 million annually, during 1990 to 1998, to 5 million or less during 1999 to 2006 (Table 3).

American shad eggs were also obtained from a tank-spawning effort at Conowingo Dam, operated by Normandeau Associates. Pre-spawn adult American shad were obtained from the West Fish Lift at Conowingo Dam, injected with hormones and allowed to spawn naturally. Some 10.3 million eggs, in 17 shipments, were delivered to the Van Dyke Hatchery, with a viability of 21.7%. By comparison, 8.0 million eggs, in 11 shipments, were received from this source in 2005. This has become a consistent source of eggs for the restoration program, but viability has been low, ranging from 10% to 33%.

SURVIVAL

Overall survival of American shad larvae was 74% compared to a range of 19% to 94% for the period 1984 through 2005. The 13% decrease in survival from 2005 (87%) was due, in part, to mortality in 12 tanks from various egg sources (Figure 2).

Figure 2

Survival of individual tanks followed patterns similar to those observed in the past. Eighteen tanks, reared from 16 to 27 days of age, exhibited 26-d survival of 87% (Figure 2). High mortality episodes occurred in 12 tanks after nine days of age. One tank, Potomac River egg source, exhibited 23-d survival of 67%. Two tanks, Susquehanna River source, exhibited 18-d survival of 60%. Five tanks, Delaware River source, exhibited 22-d survival of 58%. Four tanks, Hudson River source, exhibited 20-d survival of 44%. These mortality episodes occurred across egg sources and egg jar types. Higher mortality tanks were reared later in the rearing season: all tanks exhibiting less than 60% survival were hatched on or after May 17. The cause of these mortalities is unknown, although pH or physical damage may have played a role. Van Dyke influent pH ranged from 5.7 to 6.2 with a mean of 6.0 and no trend over time. By comparison, in 2005, pH ranged from 5.7 to 6.5 with a mean of 6.2 and a clearly increasing trend over time from 5.7 early in the season to 6.2 in mid-season and 6.4 by the end of the season. Since before 1985, 50 pounds of lime has been spread on the spring pond bottom annually, before filling, to provide some buffering for the soft, sandstone source water. Sometime prior to 1985, a load of crushed limestone was deposited in the influent end of the warming pond. We will add additional limestone in 2007 to attempt to further buffer the influent water.

Specimens from a high mortality tank were supplied to the PFBC pathologist who filed the following report: “Other than the abnormal eye condition that I showed you (apparent physical damage to the eye) , I did not observe any other abnormalities in the shad fry from tank H4 that you delivered on 6/19/06. The portions of the gills that I could see, were normal in structure. One fish had several protozoans, presumptively identified as Costia, on and around the skin surface; however, I did not observe the organism on any of the other specimens that I examined. All digestive tracts were empty. “ The pathologist speculated that the observed eye damage on several specimens may have been due to strike trauma from over-aggressive tank spinning during tank cleaning. We will take care to be more gentle in working with the fish during 2007.

LARVAL PRODUCTION

Hickory shad larvae (2.6 million) were stocked in the lower Susquehanna River at Muddy Creek Access in the Conowingo Reservoir. Some 6.5 million hickory shad were also stocked in the Delaware River (750 thousand) and its tributaries Pennypack Creek (5.4 million) and Ridley Creek (350 thousand).

Production and stocking of American shad larvae, summarized in Tables 2, 4 and 5, totaled 4.9 million. A total of 2.7 million was released in the Juniata River, 28 thousand in the Susquehanna River near Montgomery Ferry, 315 thousand in the West Branch Susquehanna River, 274 thousand in the North Branch Susquehanna River in Pennsylvania, 164 thousand in Conodoguinet Creek, 160 thousand in the Conestoga River, 135 thousand in Swatara Creek, and 135 thousand in West Conewago Creek. Some 230 thousand and 172 thousand were provided to New York for stocking in the North Branch Susquehanna River and the Chemung River, respectively. Due to the poor egg production, no larvae were provided to New Jersey for stocking in the Raritan River. Delaware River egg collections were not sufficient to meet the goals for the Delaware River Basin. Larvae were stocked in the Lehigh River (293 thousand), the Schuylkill River (254 thousand), and the Delaware River (53 thousand). Larvae stocked in the Delaware River were allocated to replenish the Delaware for the brood stock taken there.

Table 4

 

Table 5

TETRACYCLINE MARKING

All American and hickory shad larvae stocked received marks produced by immersion in tetracycline (Table 6). Immersion marks for American shad were administered by bath treatments in 256-ppm oxytetracycline hydrochloride for 4h duration. All American shad larvae were marked according to stocking site and/or egg source. All hickory shad larvae were marked with 512-ppm and given a single mark on day 3. American shad larvae from the Susquehanna River egg source, and stocked in the Juniata River or Susquehanna River near Montgomery Ferry were given a triple mark at 3, 6, and 9 days of age. Larvae from the Hudson River egg source and stocked in the Juniata River or Susquehanna River near Montgomery Ferry were marked at 18 days of age. Larvae stocked in the West Branch Susquehanna River were given a quintuple mark at 3, 6, 9, 12, and 15 days of age. Larvae stocked in the North Branch Susquehanna River in Pennsylvania were given a quadruple mark at 3,6,9 and 15 days of age. Larvae stocked in Conodoguinet Creek were given a quadruple mark on 3,6,12 and 15 days of age. Larvae stocked in the Conestoga River were given a quadruple mark on 3,9,12 and 15 days of age. Larvae stocked in Swatara Creek were given a quintuple mark on 3,6,9,15 and 18 days of age. Larvae stocked in West Conewago Creek were given a quintuple mark on 3,6,12,15 and 18 days of age. Larvae stocked in the North Branch Susquehanna River in New York were given a quintuple mark on 3,6,9,12 and 18 days of age. Larvae stocked in the Chemung River in New York were given a triple mark on 3,15 and 18 days of age. Larvae stocked in the Lehigh River were given a triple mark at 9, 12, and 15 days of age. Larvae stocked in the Schuylkill River were given a quadruple mark at 3, 6, 9, and 12 days of age. Larvae stocked in the Delaware River were given a quintuple mark at 3, 6, 12, 15, and 18 days of age.

Table 6

Verification of mark retention was accomplished by stocking groups of marked fry in raceways and examining otolith samples collected later. Otoliths were extracted and mounted in Permount on microscope slides. A thin section was produced by grinding the otolith on both sides. Otolith sections were examined for marks with an epi-fluorescent microscope with a UV light source.

Retention of tetracycline marks for American shad was 100% for most groups analyzed (Table 6). In order to provide enough raceways, raceway sections were divided and screened to segregate groups. Several of the raceway samples contained fish which had escaped through the screens from an adjacent raceway section and exhibited the mark from the adjacent raceway. These included one fish from the West Branch Susquehanna River raceway, one fish from the Schuylkill River raceway, and five fish from the Swatara Creek raceway. Nineteen of the 20 mark retention fish from the North Branch Susquehanna River in New York exhibited the 3,6,9,12,18 mark, but one fish exhibited a mark which appeared as a 3,6,9,12,15 mark. This was most likely due to poor otolith growth between days 12 and 18. Only five of the 20 mark retention fish from the Delaware River exhibited the 3,6,12,15,18 mark. The remaining fifteen exhibited marks which appeared as a 3,6,12,15 mark (missing the day 18 mark). On the five specimens which did exhibit a day 18 mark, the mark was faint. The cause of the poor mark retention for this one mark is unknown, but may be related to immersion mark timing. This was the last mark produced in 2006, on the last tank in the hatchery. In order to complete marking and move on to other tasks, marking was begun at 8:30AM, two hours earlier than normal, which may have impacted mark retention and quality. Mark retention for fish stocked in the Lehigh River was assessed on only one fish since it was the only survivor in the raceway. Mark retention could not be evaluated for the day 3,15,18 mark (larvae stocked in the Chemung River) because none were stocked in a raceway. Mark retention was 95% for hickory shad (19 of 20 marked). Marking protocols for 2006 to 2010 are given in Table 7. The primary production mark for Hudson and Potomac source larvae stocked in the Juniata River or Susquehanna River near Montgomery Ferry will be changed every year to provide known age specimens for age verification.

Table 7

RECOMMENDATIONS FOR 2007

  1. Disinfect all egg shipments at 50 ppm free iodine.
  2. Slow temper eggs collected at river temperatures below 55°F.
  3. Routinely feed all larvae beginning at hatch.
  4. Continue to hold egg jars on the incubation battery until eggs begin hatching (usually day 7), before transferring to the tanks. Transfer incubation jars to the tanks on day 7 without sunning. Sun the eggs on day 8 to force hatching.
  5. Continue to siphon eggshells from the rearing tank within hours of egg hatch.
  6. Continue to feed left over AP-100 only if freshly manufactured supplies run out.
  7. Continue to hold Delaware River eggs until 8:00AM before processing.
  8. Buy new foam bottom screens each year and specify “no-fire retardants” when ordering foam.
  9. Modify the egg battery to accept 23 additional MSXXX jars (total 57).
  10. Continue to collect American shad eggs from the Potomac River as an additional source of out-of-basin eggs.
  11. Continue to develop a reference collection of scales and otoliths from known age American shad by marking according to year stocked (Table 7). Utilize larvae from the Hudson and Potomac River egg sources, stocked in the Juniata or Susquehanna Rivers, and uniquely marked on a three year rotating schedule.
  12. Mark hickory shad at 512ppm OTC.
  13. Continue using Pfizer Terramycin 343 (now FDA approved) for marking alosines.
  14. Attempt to buffer Van Dyke influent water by adding crushed limestone to the influent end of the warming pond.
  15. Be more gentle when spinning the tank for cleaning.
  16. Mark all tanks of larvae beginning at 11:00AM, regardless of other considerations.

REFERENCES

Hendricks, M. L., T. R. Bender, Jr. and V. A. Mudrak. 1991. Job III. American shad hatchery operations. In: Restoration of American shad to the Susquehanna River, Annual Progress Report, 1990. Susquehanna River Anadromous Fish Restoration Committee.

Hendricks, M. L., T. R. Bender, Jr. and V. A. Mudrak. 1992. Job III. American shad hatchery operations. In: Restoration of American shad to the Susquehanna River, Annual Progress Report, 1991. Susquehanna River Anadromous Fish Restoration Committee.

Hendricks, M. L. and T. R. Bender, Jr. 1993. Job III. American shad hatchery operations. In: Restoration of American shad to the Susquehanna River, Annual Progress Report, 1992. Susquehanna River Anadromous Fish Restoration Committee.

Hendricks, M. L. and T. R. Bender, Jr. 1994. Job III. American shad hatchery operations. In: Restoration of American shad to the Susquehanna River, Annual Progress Report, 1993. Susquehanna River Anadromous Fish Restoration Committee.

Hendricks, M. L. and T. R. Bender, Jr. 1995. Job III. American shad hatchery operations. In: Restoration of American shad to the Susquehanna River, Annual Progress Report, 1994. Susquehanna River Anadromous Fish Restoration Committee.

Hendricks, M. L. 1996. Job III. American shad hatchery operations. In: Restoration of American shad to the Susquehanna River, Annual Progress Report, 1995. Susquehanna River Anadromous Fish Restoration Committee.

Hendricks, M. L. 1997. Job III. American shad hatchery operations. In: Restoration of American shad to the Susquehanna River, Annual Progress Report, 1996. Susquehanna River Anadromous Fish Restoration Committee.

Hendricks, M. L. 1998. Job III. American shad hatchery operations. In: Restoration of American shad to the Susquehanna River, Annual Progress Report, 1997. Susquehanna River Anadromous Fish Restoration Committee.

Hendricks, M. L. 1999. Job III. American shad hatchery operations. In: Restoration of American shad to the Susquehanna River, Annual Progress Report, 1998. Susquehanna River Anadromous Fish Restoration Committee.

Hendricks, M. L. 2001. Job III. American shad hatchery operations. In: Restoration of American shad to the Susquehanna River, Annual Progress Report, 2000. Susquehanna River Anadromous Fish Restoration Committee.

Hendricks, M. L. 2002. Job III. American shad hatchery operations. In: Restoration of American shad to the Susquehanna River, Annual Progress Report, 2001. Susquehanna River Anadromous Fish Restoration Committee.

Hendricks, M. L. 2003. Job III. American shad hatchery operations. In: Restoration of American shad to the Susquehanna River, Annual Progress Report, 2002. Susquehanna River Anadromous Fish Restoration Committee.

Hendricks, M. L. 2004. Job III. American shad hatchery operations. In: Restoration of American shad to the Susquehanna River, Annual Progress Report, 2003. Susquehanna River Anadromous Fish Restoration Committee.

Hendricks, M. L. 2005. Job III. American shad hatchery operations. In: Restoration of American shad to the Susquehanna River, Annual Progress Report, 2004. Susquehanna River Anadromous Fish Restoration Committee.

Hendricks, M. L. 2006. Job III. American shad hatchery operations. In: Restoration of American shad to the Susquehanna River, Annual Progress Report, 2005. Susquehanna River Anadromous Fish Restoration Committee.


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