Hoki and Ling Proteins

 

Hoki is an abundant, fatty pelagic fish (Macruronus magellanicus) that has important commercial and recreational value to Chile and Argentina. It also spawns in the Southwest Atlantic and Southeast Pacific. Hoki is an important target species for trawl fisheries.

In order to reduce incidental mortality of albatrosses and petrels interacting with New Zealand’s Hoki mid-water and bottom trawls, the New Zealand Ministry of Fisheries issued Seabird Scaring Devices Circular 2010 (see http://www.govt.nz/publications/circulars/page/1209). In this circular trawlers were required to deploy one of three mitigation measures to reduce bird impacts: paired hoki bird-scaring lines, a bird baffler or a warp deflector.

Using RVA, we measured the temperature at which hoki and ling skin collagens begin to denature (denaturation temperature, TD). For both fish, the TD increases logarithmically with heating rate and is related to the difference in temperature-time histories that the proteins undergo [5,6].

The TDs determined for hoki and ling skin proteins were compared with results from other fish species. The TD for salmon skeletal muscle, for example, was lower than that for hoki and ling. This may reflect differences in the composition of the fish tissue and/or the chemistry of its proteins.More Details Pp hoki 

The TDs of hoki and ling were also used to calculate the protein concentration at which homogeneous denaturation occurs, known as its isoelectric point (pI). This metric is important for determining the quality of protein purifications. The pI of hoki and ling was approximately the same, indicating that the peptide chains of these fish are well oriented in solution. This is consistent with a previous study on the lipids of hoki that found that their lipid structures were highly polar. The polarity of these proteins is likely to influence their stability and membrane-forming ability. This work demonstrates the usefulness of combining results from otolith microchemistry with those from parasite tags in estimating egg production and in predicting migration patterns.