From professional motorbike racing to an innovative fishbox initiative - Magnus Houston has packed a lot into just three decades of life.

Miles away from the race track, and miles away from his former life, Magnus Houston surveys the skyline. He has driven us, rally-style, from Inverness in order to make it to Avoch harbour in good time to see a fisherman land his catch of shellfish. The fisherman in question, Thomas, has not yet arrived, so to kill time we walk around the harbour to look at the creels. Magnus explains to me how they work, with the lobster entering through a netted tunnel into the belly of the thing. The simplistic nature of the device is comical - how can these contraptions still be the best way of harvesting lobster? Because there is no waste, I am told. And because anything unwelcome that crawls in can use the creel as a temporary home before being returned to the ocean unscathed. It is to be the beginning of a startling education about the state of ethical fishing.

Magnus, owner of Coast & Glen, is well-versed in how all the fishing paraphernalia works because he used to be a fisherman. So far, so unsurprising. But before a fisherman, he was a motorbike racer signed to Suzuki. An accident rendered racing a thing of the past, and so after taking a trip out in a friend's boat he decided to buy his own and began fishing himself full-time. Full-time seems an understatement though, because fishing isn't really a job - it is a life, and it changes you. He came to curse sunny weather in summer, taking his boat out at 3am and fishing 'til midday, covering his catch in wet duvets to preserve it in the heat. Then he'd return home in the warmest hours, eat a stodgy meal and sleep until his partner returned from work, then get up for the evening and return to bed when she did at night. I wonder how warm it can actually be on an Invernesian coast, but I have not, of course, factored in how a top-to-toe waterproof suit can make a body sweat.

With help from the Prince's Trust combined with his own savings, Magnus progressed from fishing by himself to Coast & Glen - his business that involves supplying local restaurant and hotels with fish and shellfish landed by local fishermen with small boats like Thomas, who we have come to Avoch to meet. After the locale has been supplied to, the extraneous produce caught can be exported to France and Spain - which is where the real money comes from. It is a back-to-front business model from many others, who sell the majority of what they catch on Scottish seas to the export market.

Thomas lands his boat, and chats to Magnus in an easy fisherman's code - to me it sounds like almost a completely different language, like the shipping forecast. All their points of reference are different from my own: when Magnus asks Thomas what the day has in store, he answers in wind directions rather than weather-girl speak.

Thomas is built like a classic fisherman, I am told: inimitably strong. His body is one of his best tools when out at sea - that solidness ensures that he can use himself as a buffer, or a dead-weight, or an anchor should he need to. "Your day ends when your body tells you it's time to finish" he says. But his skills transcend what can be taught and what the body can be trained to do - he has a fisherman's sixth sense of pre-empting danger, and keeping numerous other factors in his mind when approaching a task when out at sea. If he is pulling in his creels he knows where the ropes that snake through the bottom of the boat looking to ensnare thoughtless feet are at all times. And it is not just being able to work the boat: it is intuition and relentless hazard perception, like a driving instructor of the sea.

I ask if he is enjoys his job, and I apologise for what seems like such a simplistic question because it is clear that he does, despite the hardships, but I want to hear his answer. He asks me if I enjoy mine: I say that when I'm doing well, writing well, I do. And when I'm not performing, when I can't get to the core of something, then I don't. He feels the same way. Coast & Glen is able to support local fisherman like Thomas by paying them fair prices depending on how much they catch, rather than just a flat-rate. "You always put it away though, whatever you earn" says Thomas. "Whatever you make, you have to keep in mind how much your bait will be, plus your fuel, and all the other things that have to come out of the money".

Magnus and Thomas transfer the catch from his boat to large boxes ready to be loaded into the van. There are colours that I didn't know could appear in nature: inky blue lobster claws, fan-shaped protective armour with orange fringing which has dried into tiny isosceles triangles. Thomas is particularly pleased with one of the smaller lobsters and takes me on to the boat to show me that it is exactly the smallest size a lobster can possibly be in order to be sold, down to the millimetre. He uses a level-yellow triangle to ascertain its size, measuring from the back of the eye socket down to the rear of the carapace, or exoskeleton. A benchmark lobster.

Back at the Coast & Glen unit, Magnus prices up Thomas's haul with Korri and Andy. He shows me the sum of what Thomas will receive for two days' work, and to the untrained eye it seems more than reasonable. Will Thomas get to eat what he catches? I ask, wondering if there is some level of painful irony with what he works with all day and what he is allowed to take away. "He'll probably take the cripples [lobsters or crab missing a claw] home with him, yes" Magnus replies. "But often after a day at sea, he'll want something rich and carb-heavy for his tea rather than preparing and serving something like shellfish." It is a pragmatic point that feels embarrassingly obvious to my always-on-the-lookout-for-injustice mind.

 While Magnus is at a meeting (life goes on around journalists getting in the way of things, of course), 20-year-old Korri shows me how to fillet a lemon sole.  Part-trained as a butcher, he fluidly navigates the fish like a dressmaker: a small slit here, a deft turn of the tool there, making geometrically aligned incisions drawn from a remembered pattern.  He is also a superb teacher, complimenting my raggedy results which sit on the worktop next to his gleaming suppers.

Later on, I sit with Fiona, Magnus's partner and a trained physiotherapist as well as Coast & Glen's social media manager. We Google super trawlers due to, in part, my lack of knowledge and Fiona's curiosity. Coast & Glen is not just about supplying fresh, beautiful fish to trade, though that makes up about 85% of what the company does. It also pioneers its fishboxes - an initiative that works much like the Graze box, whereby customers can pay a given amount and receive a lucky bag of fish, depending on what has come in. Earlier in the day Magnus relayed a story of one of his first fishbox customers, who had concerns about the quantity of her delivery compared to what she could buy in the supermarket for a similar price. The two products, Magnus explained, were almost entirely incomparable: in the supermarket, we buy fish claiming to be Scottish but can in fact be caught on super-trawlers in Iceland, taken to the hub in London to be distributed, filleted in another location, and taken back up to Scotland to be smoked before being sold. It has also been frozen with liquid nitrogen at some point in its journey, damaging the fish's flavour and texture irrevocably. It is an entirely different product, but if it has been 'amended' in some way in Scotland, it is just a case of dancing around the wording of the term 'Scottish fish'.

And of those super-trawlers. The word is something of a misnomer, because there is nothing in the least super about how these boats catch their hauls. The nets super trawlers use are each large enough to hold 13 jumbo jets and destroy entire shoals of fish at a time, thus preventing the shoal from regenerating in any way. The nets are not discerning about what they catch - endangered sharks, rays and turtles are swept up and then thrown back in, useless and dead. It is a vast issue - and one that there is not nearly enough ready and impartial information for the masses.

More happily, however, is Coast & Glen's enabling of fish-lovers to purchase its boxes of local sustainable produce from anywhere in the country. They have customers in London, Hertfordshire and Yorkshire, and of course, many in Scotland. The fish they will eat has made a short journey - fishing-line shaped - from where it was caught to where it is delivered, rather than the supermarket's spiderweb. Where the 'Scottish' fish we buy in a supermarket can be 15 days old (Iceland is a fair distance to travel back from, after all), Coast & Glen's can be on the dinner table in two or three.

Back in Glasgow, I make the lemon sole Korri helped me fillet into a supper with spring greens and samphire that takes less than ten minutes to create. It should be the easiest thing in the world to eat fresh, Scottish produce that is caught here in the country but often it's much more complex. Coast & Glen is attempting to simplify that process, and strengthen the relationships between component parts of the chain, one catch at a time.  

Coast & Glen's new website will be launched on May 2 at www.coastandglen.com. Details on how to purchase fishboxes can be obtained by emailing magnus@coastandglen.com. To find out more about visiting the north Highlands, visit www.northhighlandsscotland.com