Growth of farmed blue mussels (Mytilus edulis L.) in a Norwegian coastal area; comparison of food proxies by DEB modeling

Seston variables and growth of the blue mussel (Mytilus edulis L.) were measured during the growth season from March to October in three suspended longline farms in Central Norway; one in the inner part of Åfjorden (63° 56′ N, 10° 11′ E) and two in Inner and Outer Koet, respectively (63° 49′ N, 9° 42′ and 47′ E). Four seston variables were used as alternative input values in a Dynamic Energy Budget (DEB) model to compare their suitability as food proxies for predicting mussel growth: 1; total particulate matter (TPM), 2; particulate organic matter (POM), 3; organic content (OC) and 4; chlorophyll a (chl a).

Mean TPM and POM measured 6.1 and 1.9 mg L− 1 in Åfjorden, 10.3 and 4.2 mg L− 1 in Inner Koet, and 10.5 and 4.6 mg L− 1 in Outer Koet, respectively, resulting in a mean OC of 32, 41 and 44% in Åfjorden and Inner and Outer Koet, respectively. Mean chl a measured 1.6 μg L− 1 in Åfjorden, 3.1 μg L− 1 in Inner Koet, and 1.6 μg L− 1 in Outer Koet.

Average length growth was 0.20% day− 1 in medium sized mussels (24–36 mm) in Åfjorden and 0.08% day− 1 in large mussels (40–55 mm) in Inner and Outer Koet. Mean standardized soft tissue dry weight ranged between 250 and 390 mg in Åfjorden, 600 and 1175 in Inner Koet, and 600 and 960 mg in Outer Koet, and showed a seasonal pattern independent of growth in length with scattered spawnings.