Effects of shell lesions on survival, growth, condition and reproduction in the New Zealand blackfoot abalone Haliotis iris.

The pathogenicity of shell lesions in Haliotis iris Martyn was examined in a laboratory experiment in which 73 apparently healthy and 106 lesion-bearing abalone were maintained for up to 12 mo. The abalone were collected from the wild and kept in cages (1 ind. cage(-1)) for 4, 8 or 12 mo, at which times estimates of survival, growth, condition and reproductive capacity were made for each of 3 groups: 'healthy' (n = 73), 'mildly affected' (n = 61) and 'severely affected' (n = 32). Unaffected abalone showed a 2.7% mortality (n = 73) compared to 7.5% (n = 93) in lesion-bearing individuals over the entire experiment. Growth rates were significantly decreased in mildly and severely affected abalone: the relative von Bertalanffy growth coefficient (K), calculated over 12 mo, was -0.176 for unaffected, -0.079 for mildly affected and -0.048 for severely affected individuals. The asymptotic length (L(infinity)) was calculated to be 131.5 mm for unaffected, 142.1 mm for mildly affected and 150.3 mm for severely affected abalone. Significantly (p < 0.05) lower condition indices and decreased reproductive capacity (p > 0.05) were obtained for the severely affected group compared to unaffected abalone. These trends were consistent over the course of the experiment.

Evaluation of radiography, ultrasonography and endoscopy for detection of shell lesions in live abalone Haliotis iris (Mollusca: Gastropoda).

Radiography, ultrasonography and endoscopy were examined for their efficacy as non-destructive techniques for the detection of shell lesions in the marine gastropod Haliotis iris Gmelin. X-rays provided 69% correct diagnoses, with detection being restricted to those lesions which were mineralised. Ultrasound also showed potential to reliably detect lesions (83% correct diagnoses), but only where the lesions demonstrated a clear 3-dimensional relief. Lesion dimensions were underestimated using ultrasound. Endoscopy, applied to anaesthetised individuals, provided the most accurate method (92% correct diagnoses) for lesion detection and, although invasive, had no discernible effect on survival of the abalone 8 mo after screening.