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Retinal adaptations of southern bluefin tuna larvae: implications for culture

Citation

Hilder, PE and Battaglene, SC and Hart, NS and Collin, SP and Cobcroft, JM, Retinal adaptations of southern bluefin tuna larvae: implications for culture, Aquaculture, 507 pp. 222-232. ISSN 0044-8486 (2019) [Refereed Article]

Copyright Statement

Copyright 2019 Crown Copyright

DOI: doi:10.1016/j.aquaculture.2019.04.024

Abstract

We examined Southern bluefin tuna, Thunnus maccoyii, larvae to identify specific retinal adaptations that would indicate both important parameters for culture and larval ecology in the wild. Plastic resin histology, microspectrophotometry and behavioural feeding responses were used to describe visual development. Thunnus maccoyii larvae reflected the visual morphogenesis template commonly observed in many other marine fish species exhibiting indirect development. First-feeding (3 days post-hatching, [dph], 3.4 mm standard length [SL]) larvae possessed tightly packed single cone photoreceptors. Rods and twin cones were present in the retina in post-flexion larvae (21 dph, 8.39 mm fork length [FL]) with cone mosaic patterns observed in juveniles (30 dph, 21 mm FL). Based on the spacing of adjacent photoreceptors and focal length, first feeding larvae had a maximum theoretical visual acuity of 1.23  0.11 that decreased to 0.14  0.02 at 30 dph. Thunnus maccoyii displayed high cell density in the ventral retinal region (cones, bipolar and horizontal cells), a low convergence of cone cells to ganglion cells throughout the retina during larval development (1.1  0.2 to 1.4  0.3 at 3 dph and 30 dph, respectively), and early development of retinal pigment epithelium (RPE) migration. Microspectrophotometry showed twin cone visual pigments maximally sensitive to light in the blue-green part of the visual spectrum (wavelength of maximum absorption [λmax] of 494 nm, 507 nm and 524 nm), and behavioural experiments showed they fed preferentially at these wavelengths. Increased retinal cone densities in the ventral region indicated a localized region specialized for acute vision for prey and predator detection in the upward direction (dorsal plane) at an early age, representing a possible adaptation to life in deeper oceanic waters. The apparent high acuity and photopic sensitivity observed in T. maccoyii is hypothesised to be associated with the ability to feed in low light conditions. This has important practical considerations in determining lighting regimes for culture of T. maccoyii and possibly for other tuna species.

Item Details

Item Type:Refereed Article
Keywords:vision, fish larvae, eye development, microspectrophotometry, light, spectral sensitivity and retina
Research Division:Agricultural, Veterinary and Food Sciences
Research Group:Fisheries sciences
Research Field:Fish physiology and genetics
Objective Division:Animal Production and Animal Primary Products
Objective Group:Fisheries - aquaculture
Objective Field:Aquaculture tuna
UTAS Author:Hilder, PE (Mrs Polly Hilder)
UTAS Author:Battaglene, SC (Associate Professor Stephen Battaglene)
UTAS Author:Cobcroft, JM (Dr Jennifer Cobcroft)
ID Code:139814
Year Published:2019
Web of Science® Times Cited:4
Deposited By:Fisheries and Aquaculture
Deposited On:2020-07-07
Last Modified:2020-08-28
Downloads:0

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