By Michael MacDonald THE CANADIAN PRESS HALIFAX- An Indigenous fisherman appeared Thursday in a northern New Brunswick courtroom, where he began a constitutional challenge that could prove pivotal for First Nations across the Maritimes. Cody Caplin, a member of the Eel River Bar First Nation, was fishing for lobster in the Bay of Chaleur in September 2018 when he and his brother Kyle were arrested and their boat was seized by federal fisheries officers. A year later, they were charged with 10 fishing offences, including trapping lobster out of season. Caplin says his brother eventually pleaded guilty to the charges, mainly because of the financial burden of going to trial. But Caplin has pressed on, claiming the Mi’kmaq have constitutionally protected Indigenous and treaty rights to fish and hunt to…