Anchor tags affect swimming performance and growth of juvenile red drum (Sciaenops ocellatus)

ABSTRACTBetween August and December 2013, the offshore cages of a commercial marine farm culturing red drum Sciaenops ocellatus in Campeche Bay were affected by an outbreak of an ulcerative granulomatous disease, reaching 70% cumulative mortality. Thirty-one adults displaying open ulcers on the skin were submitted to our laboratory for diagnosis. Multiple white-yellowish nodules (0.1-0.5 cm in diameter) were present in all internal organs, where the kidney and the spleen were the most severely affected. Histopathological observations of these organs evinced typical granulomatous formations. Gram and Ziehl-Neelsen stains on tissue imprints, bacterial swabs and tissue sections revealed Gram-positive, acid-fast, branching beaded long rod filamentous bacteria. Tissue samples resulted positive for nocardiosis when a Nocardia genus specific nested PCR was used. Definite identification at the species level and taxonomic positioning of the fastidious pathogen was achieved through a specific Nocardia seriolae PCR and by sequencing the gyrB gene of pure isolates. After application of antibiotics during fry production, a posterior follow-up monitoring (from 2014 to 2017) detected mild but recurrent outbreaks of the bacteria with no seasonality pattern. To the extent of our current knowledge, this is the first report of piscine nocardiosis (in a new host -red drum) in Mexico.

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To fight, or not to fight: determinants and consequences of social behaviour in young red drum (Sciaenops ocellatus)

Behaviour ◽

10.1163/156853909x446226 ◽

2009 ◽

Vol 146 (6) ◽

pp. 815-830 ◽

Cited By ~ 5

Author(s):

Shinnosuke Nakayama ◽

Alfredo Ojanguren ◽

Lee Fuiman

Keyword(s):

Body Size ◽

Social Interactions ◽

Social Behaviour ◽

Physiological State ◽

Developmental State ◽

Red Drum ◽

Sciaenops Ocellatus ◽

Competitive Disadvantage ◽

Nursery Habitats ◽

Wet Weight

Abstract Social behaviour is critical for survival and fitness in many organisms. The aim of this study was to examine the effects of developmental state, physiological state and their differences between individuals on the intensities of aggressive and grouping behaviours in red drum (Sciaenops ocellatus) larvae. Body size was used as a proxy for developmental state and body condition (i.e., residual of wet weight from the relationship between body size and wet weight) as a measure of physiological condition. Social interactions between two fish were observed for 30 min in a 9-l tank. We found that the duration of grouping behaviour increased as body size increased, but aggressive behaviour was less frequent as body size and condition increased. The larger fish in a trial tended to be aggressive to the smaller one, and fish of similar sizes tended to show grouping behaviour. Fish that more frequently displayed aggressive behaviours tended to occupy the lower part of the water column. Body size and condition were important determinants of social interactions between red drum larvae. Our results suggest competitive disadvantage for the larvae from late cohorts when they recruit to the nursery habitats where larger larvae from early cohorts have already occupied.

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