Over at Brexit Central, Madsen has written about his plan to restore Britain's fisheries using property rights and market mechanisms – the Icelandic model, essentially:

Having seen its fish stocks depleted by over-fishing, Iceland instituted a quota system to restore and sustain them.  Each year its scientists estimate the biomass within Iceland’s waters.  They measure the amount and size of a variety of different species and calculate the quantity of each that can be fished sustainably.  Quotas of different types of fish are assigned to every boat, quotas which belong to the owners and which, crucially, can be traded.

Every catch is recorded, and no dumping is allowed.  All catches must be landed, and if a boat exceeds its quota for a type of fish, its owners must buy quotas from others to stay within the law. All catches and quota trades have to be made public, and are put online so that any vessel can inspect the current state of the market, and decide what and where to catch based on public information.

Read his post here, and his recent paper on these proposals here.