My journey to the Shakotan Peninsula, a scenic corner of Hokkaido known for its sea urchin, salmon, herring and other fish, actually began in New York more than 30 years ago when my father took me for sushi at a Japanese restaurant near his office in Lower Manhattan.

Our occasional visits were an exotic treat for a suburban kid raised on steak and pasta. When I was in my teens, my father decided to expand my horizons and ordered uni, or sea urchin. To his surprise, I loved its sublime taste and gelatinous texture.

Uni became my litmus test for sushi fans. In college, I dared friends to try it. After graduation, I moved to Japan and sought it out. When I worked in the Tokyo bureau of The New York Times a decade ago, I often walked across the street to Tsukiji Fish Market, the world’s largest wholesale fish market, to dine on sushi — and, especially, uni.

On our annual visits to Japan since then, my wife and I stay near the market so we can take in the fabulous seafood. A few years ago when we visited the seaside town of Shimoda, we met a woman on the beach with a bucket of uni. She generously cut two open so we could taste the sweet roe inside.

As good as it was, I knew that the freshest uni was in Hokkaido, the northernmost of Japan’s four main islands. So in June, we took a 90-minute flight from Tokyo to Sapporo to visit the source.

Our timing was good. While the rest of Japan was sweltering and wet, Hokkaido was bathed by soft breezes and sunshine. Everything was in bloom, including the ubiquitous lavender whose fragrance reminds visitors how far they are from gritty Tokyo.

Mid-June was also the start of uni fishing season on the Shakotan Peninsula, two hours west of Sapporo, Hokkaido’s capital and largest city. No trains run as far as the town of Shakotan, so we rented a car and drove past Sapporo’s sprawl until we hit a coastal road that bordered Ishikari Bay. Tokyo’s bustle and concrete seemed a world away.

Frontier land

With 5.5 million people spread across an area a bit smaller than Maine, Hokkaido is roomy by Japanese standards. With lush forests and dramatic coastlines, the island is still considered a frontier by the Japanese, who settled there in earnest less than 150 years ago.

Like Maine, Hokkaido is a seafood lovers’ paradise. As we drove northwest, it seemed we had entered an uni festival. First in Otaru, then in the smaller port towns of Yoichi, Furubira and then Shakotan, banners flapping in front of restaurants and shops celebrated the arrival of sea urchin.

We stopped for lunch in Shakotan, a town known for its stunning capes, reefs and blue waters that are part of a marine sanctuary. We chose Fuku Zushi, a modest sushi bar that, based on the pictures on the walls, had been featured on television shows.

At the counter, I ordered sanshoku chirashi (2,100 yen, or $21.50 at 98 yen to the dollar), a lacquer bowl filled with uni; ikura, or salmon eggs; and hotate, or scallops, on a bed of rice with wasabi, mint leaf, sliced cucumber, ginger and pickles. The ikura popped in my mouth, the hotate was buttery soft and the uni was creamy and sweet without a seafood aftertaste, the kind of freshness I was hoping we would encounter when we left Tokyo.

There are more than 100 varieties of sea urchin in Japan, but only six are edible. A chef, Kiichi Sasaki, explained that two types are caught nearby: Murasaki uni, which has a mustard yellow color and a sweet taste, as well as longer tentacles on the outside, and bafun uni, which has an orange hue and a richer taste.

Whatever the type, uni is not for everyone. Compared with the meaty red and silver cuts of fish on most sushi plates, uni can taste like briny Jell-O. People who are turned off by the idea of eating roe are unlikely to go for uni, either. But for connoisseurs, Shakotan is the place to be between mid-June and mid-August, when the uni is at its freshest. Sasaki said some customers visit several times a season.

The uni from Hokkaido is the most prized because of the kombu, or kelp, that they feed on, and the clean water where they live. According to Sasaki, uni caught along the Shakotan Peninsula “sets the price in Tsukiji,” in Tokyo, where a small box can sell for hundreds of dollars, three to four times more than in Hokkaido. To keep up with demand, Japan imports uni from New England, Russia, China and elsewhere, though Sasaki said these varieties were not as sweet.

While locally caught fish is often preferred, the Japanese have become anxious about the contamination of their food supply in the wake of the nuclear crisis in Fukushima. But Sasaki, the third generation in his family to run the 62-year-old sushi bar, said that fish caught in the Sea of Japan, on the opposite side of the country from Fukushima, was safe.

Catching uni

We wanted to learn more, so Sasaki called Tetsuji Jin, who helps run the East Shakotan Fishing Cooperative. Jin, who had a fisherman’s ruddy complexion, welcomed us into his living room, where we talked over tea.

Fishing for uni is labor intensive and unpredictable but, if the uni are large enough, relatively profitable, he said. The challenge is finding the time. At 4:30 a.m. each day, Jin and other fishermen get to port to learn from a spotter, who went to sea earlier, whether the waters are calm enough to fish. If they are too rough, the fishermen fix their equipment, dry fish or do other chores.

“The problem is we have a lot of days off because of the wind and weather,” Jin said.

If the weather cooperates, the fishermen set out at 5 a.m., and for no more than three hours they lean over the side of their boats and look through a large glass to spot uni several feet down. They use a long rod with a three-pronged claw at the end to grab the uni, which are about the size of a golf ball.

Uni live about 10 years, but they are most delicious at around 4 to 5 years old. Finding them, Jin said, has become tougher. In other parts of Hokkaido, sea otters have decimated the uni population. Warmer ocean temperatures have stunted the growth of the kelp that uni eat. In Shakotan, deforestation has led to runoff, upsetting the uni’s ecosystem. Signs around the harbor warned of poachers.

Never enough

We wanted more uni, so we drove back to Sapporo, stopping on the way in Otaru, a midsize port known for its sushi bars and century-old stone warehouses and glass shops. On Sushiya-dori, a street lined with restaurants, many with plastic sushi in their front windows to help tourists determine what is served inside, we found Otaru Tatsumi Sushi.

Inside, the chef, Shinya Takami, used a metal tool to split open a few live bafun uni. With a small spoon, we scooped out the five roe sacs that were covered by a brown goo that formed the guts of the sea urchin. As we devoured its innards, the uni’s tentacles kept moving in every direction.

After that, our seasonal selection of sushi that included locally caught salmon was positively tame.

The next morning, we walked to Nijo fish market in Sapporo. A fraction of the size of Tsukiji, it was a bit underwhelming, though we did see large king crab being sold for 18,500 yen, or $189, each.

We took a 40-minute train ride back to Otaru. From the station, we ambled toward the port, taking in the city’s distinctive architecture, including the century-old former branch of the Bank of Japan that symbolized Otaru’s onetime status as the Wall Street of the North.

Then we found counter seats at Masa Zushi, one of Otaru’s best known sushi bars. The mood was decidedly upscale, with classical music in the background. Toshikazu Komatsu, our stern chef, suggested an appetizer of grilled steak served with roasted garlic chips. That was followed by tofu with a dash of green tea salt.

The highlight, though, was ika somen, thin strips of squid on a bed of seaweed and sliced radish. A dollop of uni with roasted seaweed sat on top of the squid. We dipped all of it in a sauce mixed with an egg yolk. The mix of crunchy radish, buttery squid and salty seaweed was delectable when mixed with egg and uni.

Once again, the sushi that followed was superb. But my taste buds kept wandering back to the ika somen and the uni that came to define our visit here — a trip that seemed to complete the journey my father unwittingly triggered decades ago when he first urged me to try sea urchin.

If you go

• Fuku Zushi, Oaza Bikunicho, Aza Funama 102, Shakotan Town; 81-135-44-2073; 2,100 yen ($21.50) for sanshoku chirashi sushi lunch set.

• Otaru Tatsumi Sushi, 1-1-6 Hanazono, Otaru; 81-134-25-5963; about 3,000 yen for seasonal sushi selection.

• Otaru Masa Zushi, 1-1-1 Hanazono, Otaru; 81-134-23-0011; 3,150 yen for sushi set.