MANOOCH and BARANS: DISTRIBUTION AND ABUNDANCE OF TOMTATE 



P = average population expressed as 

 kilograms per km 2 in the /?th 

 depth zone, and 



A h = total area of the Mh depth zone. 



The sweep of the "3/4 Yankee trawl" was 8.748 m 

 (Azarovitz 6 ), and 3.241 km was the distance cov- 

 ered during a standard trawl. It should be noted 

 that all estimates were minimum estimates be- 

 cause the sampling efficiency of our gear with 

 regard to tomtates was unknown. Standing stock 

 values calculated for sandy-bottom areas incor- 

 porated such a large number of zero catches that 

 the transformation did not normalize the data, so 

 the resulting values should be considered sus- 

 pect. 



Age and Growth 



Scales, otoliths, fish lengths, and fish weights 

 were collected from 1,496 tomtates from the rec- 

 reational headboat fishery operating from North 

 Carolina to Cape Canaveral from 1972 through 

 1978 and from approximately 100 juvenile fish 

 collected by research trawling off South Caro- 

 lina. Total fish length was recorded in milli- 

 meters and weight in grams. 



Scales were removed from beneath the tip of 

 the posteriorly extended pectoral fin, soaked in a 

 one-tenth aqueous solution of phenol, cleaned 

 and mounted dry between two glass slides, and 

 viewed at 40X magnification on a scale projector. 

 Measurements were made and recorded from 

 the scale focus to each annulus and to the scale 

 edge in the anterior field for marginal increment 

 analyses and back-calculating fish length at the 

 time of annulus formation. 



Otoliths (sagittae) were removed by making a 

 transverse cut in the cranium with a hacksaw 

 midway between the posterior edge of the orbit 

 and the preopercle. The skull was pried open and 

 the otoliths were removed with forceps, washed 

 in water, and stored dry in labeled vials. Rings 

 were counted by placing the otoliths in a black- 

 ened-bottom watch glass and then viewing the 

 structures through a binocular dissecting micro- 

 scope with the aid of reflected light. Some of the 

 otoliths from large (older) fish were sectioned 



with a Buchler, Isomet, 1 1-1 180 7 low-speed saw 

 to facilitate aging. Measurements were not re- 

 corded from otoliths since these structures were 

 used only as a method of validating age deter- 

 mined by reading scales. 



Lengths by age for fish from all years com- 

 bined were back-calculated from a scale radius- 

 fish length regression. The regression equation 

 was based on the relationship of magnified (40X) 

 scale length to total fish length. Since a majority 

 of the scale measurements were clustered 

 around a relatively narrow size range, we based 

 our regression on a subsample of scale radius and 

 body length measurements. After grouping the 

 measurements into 25 mm body length intervals, 

 we selected approximately 12 from each interval 

 to ensure that the regression provided good 

 representation. The prediction equation took the 

 form TL = a SR 1 '; where TL = total length, SR 

 = scale radius, a = intercept, and b = slope. We 

 substituted the means of the distances from the 

 focus to each annulus for SR in the above equa- 

 tion, calculated the mean fish length for the time 

 of each annulus formation, and then calculated 

 mean growth increment for each age group. 



Calculation of a theoretical growth curve is 

 useful in modeling of growth in natural popula- 

 tions of fish. Growth parameters such as theo- 

 retical maximum attainable size (LJ, growth 

 coefficient (K), and theoretical time of the begin- 

 ning of growth (to), may be used in constructing 

 population models. The most popular theoretical 

 growth curve, the von Bertalanffy (l t = L^{\ — 

 exp — K(t — to))) was fitted to back-calculated 

 length at age data (Ricker 1975; Everhart et al. 

 1975). This particular equation also allows us to 

 make comparisons with results obtained by 

 other researchers. 



The growth parameter, L x , was first derived 

 by fitting a Walford (1946) line: Z, +1 = L x (1 - k) 

 + kl, to back-calculated data where h = total 

 length at age t, and k = slope of the Walford line. 

 The slope (A - ) is equal to e*, thus our first estimate 

 of K = In k. Preliminary values of L x were ob- 

 tained by solving the equation L x = ^-intercept/ 

 (1 — k), and by regressing annual growth incre- 

 ment (X) against fish length at the beginning of 

 the incremental period ( Y) (Jones 1976). By plot- 

 ting log e (L^ - l t ) against t and by using trial val- 

 ues of L„ ranging from lower than the prelimi- 



6 T. Azarovitz. Northeast Fisheries Center Woods Hole Lab- 

 oratory. National Marine Fisheries Service, NOAA, Woods 

 Hole, Mass., pers. commun. January 1978. 



7 Reference to trade names does not imply endorsement by 

 the National Marine Fisheries Service, NOAA. 



