60 
Fishery Bulletin 106(1 ) 
A map of Tasmania indicating the locations (black dots) from which the data on blacklip 
abalone ( Haliotis rubra) growth increment patterns were collected. Left panel represents 
the southwest region comprising three sites: BI = Black Island, GR = Giblin River, and 
HI = Hobbs Island. Right panel represents the Actaeon region (comprising two sites: the 
GP=Gagens Point and MG=Middle Ground sites) and the Bruny Island region (com- 
prising two sites: FC = Fluted Cape and OTP=One Tree Point sites). Seasonal data are 
identified by a combination of a circle and cross for both the Actaeon Island (AI) and 
Sterile Island (SI) sites (Table 1). 
tagging and recaptures were scattered throughout the 
year and the recapture intervals ranged from 0.06 to 
1.99 years. 
We tagged blacklip abalone by inserting a plastic 
rivet into the open exhalent hole furthest from the shell 
lip. The rate of tag fouling, and the increased risk of 
the tag not being found, increased dramatically after 
two years; therefore, only tags at liberty for less than 
two years were used in the analyses of seasonal growth. 
Across all sites, tagged abalone ranged in size from 47 
mm to 181 mm shell length, but ranges varied at each 
site (Table 1). Measurements of maximum shell length 
were taken to the nearest 1.0 mm. 
There is some evidence that tagging can negatively 
affect the growth of tagged animals, producing a tagging 
shock in affected individuals (Prince et al., 1988). It 
seems plausible that at least some of the variability 
in growth observed in abalone tagging experiments 
derived from different responses to the tagging process. 
In an attempt to minimize such effects in this study, 
tagging methods were standardized; animals were 
kept damp and cool during the tagging process before 
being returned to their reefs by divers. Blacklip abalone 
<50 mm shell length were not sampled because they 
tend to be highly cryptic in Tasmania, initial capture 
below this size is difficult, and adhesives rather than 
rivets, must be used to attach tags to young abalone. 
Growth model 
The units of growth used here are the growth increments 
(AL) produced by animals of known starting lengths (L t ) 
that have been at liberty for varying lengths of time (At). 
The model structure includes seasonality by default, and 
the seasonality terms are set to have zero influence to 
form an annual model. The form of the inverse-logistic 
curve used is a typical logistic selectivity curve described 
by Haddon (2001). 
Growth of blacklip abalone does not differ between 
the sexes. An inverse-logistic model was used to de- 
scribe the expected length increment AL for a known 
initial size L t : 
