Isles of Scilly Fish and Fisheries - Cornwall Wildlife Trust

Shoals of the anadromous clupeid the Allis Shad (Alosa alosa) have been caught in
the waters to the west of Scilly by vessels netting for M. merluccius.
8.9) Open water
The primary food source in open water is plankton, hence all fish in this habitat feed on
various types plankton, or the planktivorous fish and other predators that feed on it.
Most are small pelagic fish such as S. scombrus, T. trachurus, Herring (Clupea
harengus), Pilchard (Sardina pilchardus) or Sprat (Sprattus sprattus), or even the
occasional Atlantic Chub Mackerel (Scomber colias). Although only one single fish
was found by the CEFAS surveys, it is highly probable that shoals the small
mesopelagic Pearlside (Maurolicus muelleri) occur in the mid and upper waters and
are fed upon by S. scombrus in the early months of the year (Tait and Dipper, 1998).
The pelagic shoals are the prey of cetaceans and seabirds, as well as Garfish (Belone
belone) and pelagic sharks. They would also be preyed upon by billfish and tunas, but
there is no evidence of these regularly feeding in this area though they probably did in
the past. Blue Sharks (Prionace glauca) are present, especially to the south and west
of St Mary’s, from July to September. Small Porbeagles (Lamna nasus) have been
caught in August and early September, but it is probable that, as in other parts of the
south west, larger individuals are present in the winter months (De Thompson, pers.
comm., 2009).
The large planktivorous fish of these waters are the Basking Shark (Cetorhinus
maximus) and Ocean Sunfish (Mola mola); and the jellyfish hunting Leathery Turtle
(Dermochelys coriacea) may also be seen.
8.10) Mooring and pot ropes
Buoyed ropes which are in the water most of the time, such as mooring ropes and
some pot ropes quickly develop a coating of algae and sessile invertebrates. Small
fish find this cover attractive and numbers of N. lumbriciformis, small R. raninus, and,
in autumn, the spiky young of C. lumpus (Fig.1) may be found here (K. Legg and K.
Lowe, pers. comm., 2010)
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