Developmental changes in the opacity of larval herring, Clupea harengus, and their implications for vulnerability to predation

Abstract
The relative contributions of the eye, pigmentation (melanophores), and gut contents to the lateral body areas of herring larvae, Clupea harengus L., were measured using a combination of photography and computer image analysis. There was a power relationship between body area and body length (exponent 2.62) which was similar to that of the eye area (exponent 2.57) whereas the pigmented area increased at a greater rate (exponent 4.41). The area of the full gut relative to body length increased at an intermediate rate (exponent 3.04). Melanophores dilated under the effects of anaesthetic, increasing the projected pigment area of herring larvae by an average of 94% after 10 minutes of anaesthesia. These results are discussed in relation to the vulnerability of herring larvae to visual predation.