[Sam Whitefoot]

Oh yes here we go again. 2 fish out of 1000

Here is the CALCULATED population distribution for 2004 as per the ASMFC technical committee report.

Age -- Billions of fish
0 -- 406.8
1 -- 2.51
2 -- 0.67
3 -- 0.36
4 -- 0.095
5 -- 0.014
6 -- 0.003

Those numbers are at the beginning of the year when those 406 Billion age 0 fish are about 1/2 inch long. Most of those get eaten before they reach 6 inches long and 3 onces in weight.

During that same year the commercial harvest of the standing stock at age was:

0 -- 0.04%
1 -- 8.43%
2 -- 38.8%
3 -- 37.7%
4 -- 18.0%
5 -- 3.57%

Furthermore the 406 Billion fish is back calculated in the model based on a constant annual natural mortality of about 98%. Also that year 22% of the fish harvested were age 0.

Thus the Menhaden industry harvested about 40% of the (edit AGE 2) fish before they had a chance to spawn and another 40% (Age 3) before they could spawn a second time. The industry does harvest a significant number of these fish. To state otherwise is just Junebug spinning the numbers the Omega way in order to downplay the impact. Those two year old fish if left to live another year would contribute in a major way to the spawning stock and help in filtering the water in the Chesapeake Bay ecosystem.

Sam

 

[Sam Whitefoot]

From the ASMFC Fact sheet.

"One-year old menhaden are about six inches long and weigh two to three ounces, three year old menhaden are nine to ten inches long and weigh about 0.5 pound, and menhaden six years and older are about one foot long and weigh about one pound."

Thus your age zero fish don't reach 6 inches until the end of the year, not the middle as you claim. The baitfish that are caught in the middle of the summer are 2 to 3 inches long.

From the ASFMC stock assessment document, the table with the population numbers has the following as a heading:

"Table 7.3 Estimated numbers of Atlantic menhaden (in billions) at start of fishing year from forward-projecting statistical age-structured model"

The start of the fishing season for the snapper rigs is March. How big is an age 0 menhaden in March? That is where I came up with a 1/2 inch number. I don't know the exact growth rate but if it should be pretty linear during the first year and those fish would be 3 inches long in the summer and 6 inches long in December.

With respect to forage. Maybe an 18 inch striped bass will eat menhaden up to 6 inches or so. But those 26 to 50 inch fish will certainly eat a 9 inch (age 3) menhaden. Bluefish and trout will eat any size as they chop them up first.

With respect to math I corrected the wording in the last paragraph above.

Here are the numbers for the 2002 biomass and harvest at age from the ASMFC report in Billions of fish.

Age -- (spring Biomass) -- Harvest during the year
0 -- 406.8 -- 0.178
1 -- 2.51 -- 0.211
2 -- 0.67 -- 0.259
3 -- 0.36 -- 0.136
4 -- 0.095 -- 0.017
5 -- 0.014 -- 0.0005

The math to get the percentage of the standing stock harvested and the percentage of the harvest at age is pretty simple, unless you are trying to put the Omega spin on it. Did my spread sheet program add or divide something incorectly?

No matter how you stack it Omega harvest a reasonable fraction of age 1 and above fish. They harvest a substantial fraction of the age 2 and above fish. To boot most of that harvest is in Virginia's waters of the Chesapeake Bay. Many believe that the Chesapeake Bay ecosystem needs more of those age 2 and 3 menhaden swiming and filtering the water to be healthy.

Sam

 

[Sam Whitefoot]

I stand corrected on the growth rate. I guess it is non-linear during that first year. That still does not change the fact that the 400 billion age 0 fish was counted in the early spring when they were on the order of 1/2 inch long.

The distribution of harvest numbers that was given to me indirectly from NOAA was:


2004 Coastwide (preliminary)
age 0 1%
age 1 14%
age 2 72%
age 3+ 12%

2003 Coastwide
age 0 9%
age 1 18%
age 2 64%
age 3+ 9%

Here are the percentages for previous years (From the ASMFC report).


Year -- Age 0 -- Age 1 -- Age 2 -- Age 3-plus
1990 14.28% 6.15% 71.97% 7.60%
1991 27.85% 32.65% 29.88% 9.63%
1992 19.47% 35.43% 38.75% 6.34%
1993 4.26% 23.78% 61.68% 10.29%
1994 5.94% 18.40% 59.58% 16.09%
1995 3.46% 32.48% 40.88% 23.18%
1996 3.09% 19.15% 62.19% 15.57%
1997 2.53% 24.79% 42.63% 30.05%
1998 7.23% 18.36% 53.66% 20.75%
1999 18.36% 28.51% 42.68% 10.45%
2000 11.83% 17.37% 51.80% 19.00%
2001 3.44% 6.50% 55.22% 34.85%
2002 22.19% 26.36% 32.35% 19.10%

So it looks like the industry did good at catching a high percentage (>80%)of older fish in 2001, and 1996 and caught a higher precentage (>30%) of age 0-1 fish in 2002, 1999, 1995, 1992 and 1991. On average over the 14 year period between 1991 and 2004 67% of the harvest was age 2 and older and 33% was age 0 and 1.

In 2004 -- 87% of the coast wide harvest was before the end of the 2nd year which in accordance with the ASMFC menhaden fact sheet is prior to when the majority of those fish have a chance to spawn. During the 1991 through 2004 time period pre spawn (not completed they end of year 2) fish made up 83% of the harvest. That is a lot of prespawn fish.


I wonder what the population estimates were for 2004 and how many age 2 fish you left to spawn that year. And folks wonder why there is poor recruitment. If Omega was trying to help recruitment they would not be targeting the prespawn fish.

As far as striped bass are concerned. There are plenty of other predators in the bay. Flounder, bluefish, grey trout, red drum, blue crabs, herons, seagulls, osperys, to name a few. It will be interesting to see the analysis from the studies as to which species eats more or what. Also not all striped bass leave the bay at age 7 (28 inches) a certain fraction stays year round. Also those age 5 through 7 make up 20% of the coast wide popluation most of those age classes stay in the bay. Depending on the year class a good percentage of that 80% of the age 5 and less striped bass you are quoting are age 0/1 fish which do not eat those 3" to 6" inch menhaden. For instance in 2004 38% of the striped bass were age 1 fish.

Sam