More on the 2003 Year Class of Georges Bank Haddock
- Results from the 2003 NEFSC sea scallop and autumn bottom trawl surveys indicate that the size of the 2003 year class of Georges Bank haddock may be exceptionally large.
- These 9-month old haddock are currently 4-8 inches long and will not reach harvestable size or sexual maturity until 2007.
- It is vital to minimize discarding and maintain low fishing mortality until this year class matures in 2007.
- The 2003 NEFSC autumn survey age-0 haddock number per tow index was 153.4 fish, the highest ever recorded.
- Since 1963, the three largest age-0 survey indices have corresponded to the three largest haddock year classes. The 2003 age-0 index is nearly 2-fold higher than any of these indices and roughly 30-fold higher than the average during 1963-2002. Although the autumn survey age-0 index is significantly positively associated (Spearman rank correlation coefficient of D=0.80) with year class size, further monitoring of this year class will be needed to determine its size.
- The second highest age-0 index ever observed was 83.9 fish per tow in 1963.
- The 1963 year class was the largest ever observed at 486 million age-1 fish.
- The 2003 year class was observed to be very abundant and widely distributed in both the NEFSC sea scallop and autumn bottom trawl surveys. The substantial distribution of age-0 haddock south of Long Island is atypical and indicates that an unusual larval transport event occurred. A similar distribution was observed in 1987 when unusually strong along-shelf surface flows transported haddock larvae westward from spawning grounds on Georges Bank. However, haddock captured in these Southern New England strata are not included in the calculation of the Georges Bank haddock survey indices and do not affect the record-high 2003 age-0 index.
- On average, the NEFSC sea scallop survey catches less than 1 haddock per tow. In 2003, the haddock catch was 10-fold higher at over 14 haddock per tow.
- If the 2003 year class is as large as the 1963 year class, it could rapidly rebuild the haddock spawning biomass to well over 200 thousand metric tons (mt). Over its expected lifespan of 15-20 years, this cohort alone could produce on the order of several hundred thousand mt of cumulative landings if fished at the target harvest rate of F=0.20. Landings in any year would, of course, depend on the size of the 2003 year class and the magnitude of other age groups in the population.
- Georges Bank haddock spawning biomass was only 11 thousand mt in 1993 with landings of roughly 4 thousand mt.
- Georges bank haddock spawning biomass was projected to be about 120 thousand mt in 2003. This is the highest abundance of adult spawners since 1967 and a 10-fold increase since 1993.
- Historically, when haddock spawning biomass is above 75 thousand mt, the average year class size is over 5-fold larger and the odds of above average recruitment are 30-fold greater than when spawning biomass is below 75 thousand mt.
- Fishery management actions since 1994 have improved the reproductive capacity of the Georges Bank haddock. Fishing mortality on Georges Bank haddock has been below FMSY since 1995. Spawning biomass has increased more than 5-fold since 1995. Increased spawning biomass and a broader age structure of mature spawners combined with favorable environmental conditions appear to have produced an exceptional 2003 year class. If this year class is protected from discarding and high fishing mortality, it has the potential to provide significant benefits to the commercial fishery in the coming years.
- Estimates of haddock year class strength become more certain as additional survey data are collected. The 2004 Canadian and NEFSC spring bottom trawl surveys will provide additional information about the size of the 2003 year class.