38 Flat-fish or Flounder Family. 



matter of fact, the most important among the marine food-fish 

 families of market value, or some species of them, are at least 

 moderately well represented within our district's fishing area. 

 In short, the herring, mackerel, cod, salmon (i.e., smelt), mullet, 

 gurnard, eel and skate families (phis flat-fish) are all with 

 us, and yield creditable commercial results. The aim of the 

 present Report is primarily in connection with the Thames 

 Estuary, indeed only a N. shore section of it ; but to keep in 

 touch with the wider area, we have run together a general 

 sketch of the fish-fauna of our entire Fisheries District as most 

 desirable to grasp a broad view of the subject. 



The Flounder Family (Pleuronectidce) . These flat-fish are 

 well represented round the whole of our coast, more particularly 

 by the flounder, dab, plaice and sole, all of which are redundant. 

 Such forms as the halibut, turbot, brill, smear-dab, sand-sole 

 and topknots are much feebler in numbers, or are but rare. 

 While others witch, long-rough-dab, thickback (or variegated 

 sole), whiff (or sailfluke), megrim (or scald-fish) are rather 

 conspicuous by their absence, or the merest chance incursionist. 



Among the whole of the British Flounder Family the eggs 

 are of the free floating (pelagic) kind. Their transparency is 

 such that only close examination reveals their presence in the 

 sea-water, and hence fishermen seldom observe them. Driven 

 by the currents, tides and winds they may be carried and 

 hatched afar from the original spot where spawned (see p. 12). 

 Thus the resorts of very young fish does not always imply 

 the spawning grounds are there, or close by, e.g., plaice, 

 dabs and sole. 



The flat-fish are liable to variation in colour of both upper 

 and lower surface, to deviation of so called right- to left- sided 

 fish, and to partial arrest, in changed position of the eyes. 

 These physiological questions we need not enter into; but what 

 fishermen do notice is the contrast of colour assumed, according 

 to whether the ground be sandy or muddy where the fish feed. 



