Reliability of growth estimates affected by FISH shape

Many fish tagging programs rely upon information reported by fishers to estimate life history parameters (e.g., growth), including one operated by the Texas Parks and Wildlife Department (TPWD) since the 1970's.  Internal anchor tags are routinely placed in selected fish caught in gill nets in Texas bays, and reports of recaptures (including fish length) are used to estimate growth.  One of the species targeted for tagging is sheepshead (Archosargus probatocephalus).  I attempted to estimate the von Bertalanffy growth equation parameters using these data.  But, the estimates were unreliable primarily because the size at recapture was less than the size at release for over half the recaptured fish, probably a result of different measurement techniques related to the shape of the tail.  Additional research is needed to identify possible approaches to generate consistent data.  For example, an additional measurement at release that mimics the technique used by fishers at recapture could be used to calculate growth.  Until such research is conducted, sheepshead growth should be estimated from tagging programs that rely upon consistent measurements at release and recapture.