Sars' early opinion, that the question of the fluctuations in the catches was solvable but that it had to be approached from a scientific point of view, had been firmly adopted by 1890. The research programs that had been established in the preceding two decades in Russia, Norway, the United States, Scotland, Germany, England, the Netherlands, and Denmark were making rapid progress in developing the basic scientific methods needed, but were making much slower progress in developing answers to Sars' ‘obscure question’ on the causes of the ‘irregularities’ in the catches.

In the 1890s fishermen had two main complaints, as Cunningham, the biologist at the Marine Biological Association (MBA) in Plymouth, outlined (Cunningham 1895a p. 54): ‘the capture of immature or undersized flat-fish, and the decrease in the supply of the more valuable kinds of these fish.’ The fishermen's argument was that the former caused the latter, and hence, that suitable regulations on the catching of small fish would remedy the problems of the fisheries. The fishermen's first concern, the effects of the capture of small or immature fish, was often referred to as the ‘small plaice problem.’