Biogenic Calcium Phosphate from Fish Discards and By-Products

Every year, millions of tons of fish waste are generated from fishing activities, and a similar amount is discarded and returned to the sea as unwanted catches. This material can be used as a biological source for many potential new added-value products, such asobtaining hyaluronic acid from fish eyeballs or extracting collagen from fish skin, but there are not many utilities for fish bones yet. This work tackles the transformation of fish discards into calcium phosphates. Discards from scorpionfish (Scorpaena scrofa) and Atlantic horse mackerel (Trachurus trachurus), as well as by-products generated from aquaculture activities (heads and trimmings frames) of salmon (Salmon salar), were used to obtain calcium phosphate. Biphasic carbonated hydroxyapatite (HA) /beta-tricalcium phosphate (TCP) material was obtained. The biphasic HA-TCP material has a promising range of applications in the biomedical field based on its similarity to calcium phosphates found in human bones in terms of crystallite size and carbonate content. The presence of Na, Mg, Sr, and K ions in the HA-TCP material is very beneficial, since they contribute to bone metabolism and cell adhesion.

Commercial catches and discards of a Mediterranean small-scale cuttlefish fishery: implications of the new EU discard policy

The cuttlefish (Sepia officinalis) trammel net fishery is one of the most important small-scale fisheries in the Mediterranean Sea. Here we describe the main catch, by-catch and discard patterns found in this fishery on Mallorca Island by onboard surveys of 1005 netting walls from 23 fishing trips. The number of items captured, their size and their subsequent use, i.e. kept for sale or discarded, were recorded. Furthermore, the immediate survival of the unwanted items (i.e. vitality state when the gear came on board) and the medium-term survival of a subsample were assessed. The cuttlefish was the dominant species in the commercial fraction of the catch, particularly during the fishing season peak (March). However, S. officinalis catches quickly decreased further into the season, with other high-value fish, such as Scorpaena scrofa, increasing in the commercial fraction of the catch. As species composition is continuously changing, it is often difficult to determine the main target species of this fishery. This strategy possibly complicates management but maximizes fishing revenue, which was an average of €175 per trip. With respect to discards, up to 104 different species were caught but not commercialized. The most abundant were Holothuria sp. and Torpedo marmorata. Their immediate survival was 100% and 20%, respectively. In both cases, the medium-term survival and the vitality status were high after seven days in monitored captivity. Therefore, in these cases, their immediate release to the sea should be promoted, given that they are exempt from the EU landing obligation. Interviews with fishers revealed that the perceived quantity of discards was lower than the amount recorded by the present study. Currently, just a small percentage (1.5%) of these discards will be affected by the landing obligation enforced by the new European discards ban.

Scanning electron microscopy study of Strabax monstrosus von Nordmann, 1864 (Copepoda: Chondracanthidae) from Tunisian waters and histopathological study of its effects on host

Strabax monstrosus von Nordmann, 1864 (Copepoda: Chondracanthidae) is an ectoparasite and it was recently recorded from small red scorpionfish, Scorpaena notata Rafinesque, and red scorpionfish, Scorpaena scrofa L., collected from Tunisian coastal waters. Copepod females were found deeply embedded in the branchial cavity reaching the cardiac region with their mouth-parts. Observations of females and males using scanning electron microscopy showed a number of morphological features that have been previously overlooked or incompletely presented. In this study, we report for the first time the fine structures of appendages, mouthparts, external genital organs (nuptial organs), and other structures of male and female Strabax monstrosus. Histopathological study showed lesions in the cardiac region of the host fish which is the target site of the parasite. The presently reported finding is the first record of Strabax monstrosus from Scorpaena notata and Scorpaena scrofa collected from Tunisian waters.