calculous 2 question!!?

the family chauvinistic, made up of fishermen settled at lake Akira. they discover the potential that the lake held. the quantity of trouts fished per month is of 0.004x, I. - E. a quantity which is proportional to the number of trouts in the lake. to prepare the trouts in order to sell them, they use chemicals for the conservation. they reject exceeding them in the lake, which decreases the relative rate of reproduction has 1x10^-3 year

a) write the model which describes the trout population

i tried the equation dp/dt= k p(t) (M-p(t)) where k=1*10^-3 and p(t) = 0.004x

but i cant figure out what M is...or am i doing it wrong?

also i tried translating it into english from french so forgive the shitty wording