FISHERY BULLETIN VOL 



Mode 



FlGllRK 4. — Distribution of herd sizes 

 of bottlenosed dolphins for each of the 

 six replicates. 



o 



il 2 



[ I Survey 1 

 I — H Survey 2 

 (^^ Survey 3 

 ['.y\ Survey 4 

 |§§3 Survey 5 

 ^H Survey 6 



N-64 



15 20 25 



No. of individuals per herd 



K±4 



30 



35 



hcl 



ll) 



where h = mean herd size 



a = mean herd density, described as I'zL) 

 inlw) where L = total length of tran- 

 sects, n = total sightings, and iv = 

 the one-sided strip width of 0.463 

 km (0.2.5 n.mi.l. 



The estimated variance of this product (S'^((/)) was 

 calculated from Goodman (1960): 



S-Md) = h-'S-Ha)+ a'S-'(h) - S^iSlS^l/;) 



(2) 



where h = mean herd size 



a = mean herd density 

 S^(h) = estimated variance of mean herd 



size 

 S'^ta) = estimated variance of mean herd 

 density. 



Feeding was observed in portions of 36'r i23 of 

 64 ) of the groups encountered and was observed in 

 all survey periods and areas. Feeding behaviors 

 were similar to those previously reported for Tur- 

 siops sp. (Leatherwood 197.5). 



There was no correlation between the visibility 

 index and the number of sightings on any given 

 transect or set of transects regardless of how data 

 were grouped (rank correlation with Kendall's 

 Tau (Conover 1971) at a = 0.05, indicating that 

 significantly larger numbers of animals probably 

 were not missed in the most turbid water). 



TaBI.F 2. — Herd density 1 number ofherds per square kilometer), 

 mean herd size (mean number of dolphins per herdi, and dolphin 

 densities (numbers of dolphins per square kilometer) on each 

 replicate. Except where noted means and their variances were 

 calculated over replicates. 



Using ailernale method described in text Density estimate of dolphins lih = 

 542 ((rom Equation ( 1 )) Variance ot density estimate of dolphins S^id) = 

 094 (from Equation (2)) 



Manatees 



In all I made 60 sightings of manatees, totaling 

 151 animals (Figures 5, 6, 7). Sightings ranged 

 from individuals to concentrations of as many as 

 22 animals with a mean of 2.5. Animals clearly 

 identifiable as calves were part of 14 of the 60 

 sightings 123.3'^^ ) and made up 9.9'i (15 of 151 1 of 

 all manatees seen (Tables 3, 4). Intermediate- 

 sized animals, possibly yearlings or older calves, 

 were part of 5 of the 60 sightings iS.'i"! ) and com- 

 posed 3.3'/ (5 of 151 ) of all manatees seen. If these 

 intermediate-sized animals were also part of this 

 year's crop, total number of calves of the year 

 surviving at the time of the survey may be 13.2'; . 



No attempt was made to estimate numbers of 

 manatees because all manatees were recorded 

 whether on transects or connecting legs and 

 whether within or outside the transect strip. 



52 



