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Just like most natural ingredients, fish is subject to seasonal variations in both availability and quality. One of the most common causes of these variations is their spawning cycles, when certain textural changes can occur in the fish’s flesh that negatively affect its eating quality. Once the fish has moved out of the spawning stage and returned to normal feeding and growth, its flesh will return to peak condition. The changes that plaice goes through are a typical example of this; during its spawning season, which starts in the New Year, its eating quality is noticeably diminished, and doesn’t return to optimum condition until around May.

However, while it’s relatively easy to give buying guidance for plaice, for many other species it’s much less simple, as spawning seasons are not often uniform, and can also vary year on year, depending on various environmental and oceanographic factors. At Young’s, we are in continuous communication with fishermen so that we can rapidly respond to changing seasonal phenomena, ensuring that we catch fish when they’re at their best. When it comes to farmed fish, it’s a little easier, as stock can be managed in a way that avoids harvesting spawning fish and that allows production cycles to be planned in accordance with anticipated market demands.

As a consequence, farmed fish is generally available all year round without any perceptible seasonal variation in quality or supply.

In an age when consumer choice is broader than it has ever been before, it’s sometimes easy to forget that the availability of fresh seafood is subject to factors as fundamental as the state of the weather. Storms at sea can adversely affect supply, both from fishing boats and sea cage fish farms. Working patterns in the fishing industry also have an influence. Here in Britain, and in certain other fishing grounds around the globe, many fishing boats tie up for the Christmas and New Year holiday – so don’t expect to be able to buy top-quality fresh fish over that period. Religious holidays in other parts of the world can also affect fresh supplies of fish such as tuna, as can monsoon seasons in the tropics.

Despite many people’s continuing image of frozen fish as second best in comparison to fresh, it can, in fact, deliver excellent eating quality, as the fish will have been caught and frozen at the stage at which it's at the peak of its condition. Boats working in distant water fisheries will freeze fish on board within hours of it being caught, so that it doesn’t have a chance to spoil during the long journey back to port. Many of the world’s most sustainable fish stocks, such as Alaskan pollock and Arctic populations of Atlantic cod, are caught and frozen at sea in this way, ensuring that their quality isn't compromised.

But whatever time of year you buy fish, and whichever type you buy, the advice of a knowledgeable and experienced fishmonger is invaluable, so if you have one in your area, use them – they’ll be able to give you the best guidance on what’s good that day. Failing that, here’s a guide on what to look for when making your selection:

How to buy fish – a checklist

Fresh whole fish

• The eyes should be clear and convex, not sunken.

• The flesh should be firm and resilient to finger pressure.

• The fish should smell freshly and lightly of the sea. Don’t buy fish with a strong ‘fishy’ or sulphurous odour, or that smells of ammonia. Oily fish like herring, mackerel and salmon should have a light, fresh oil smell, like linseed oil. If they smell of rancid oil, don’t buy.

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