Grampus: Gray Ghosts of the Sea
The whale watchers had just circled the Farallon Islands off San Francisco, putting in briefly at Fisherman’s Bay; and now in Mirounga Bay, where they watched the seabirds and pinnipeds (seals and sea lions) hauled-out on the rocky shore, tucked up into gulches, or plying the dark waters for a meal. It was late fall, and the islands were relatively quiet; the noisy chaos of seabird nesting was over, though many sill remained. Occasionally, sea lions erupted into repetitive barking, then losing interest, fell silent. The naturalist had just recounted how she and the captain had witnessed the recent showdown between killer whales and a white shark near this very spot. But this cruise had yielded nothing so spectacular, and whale and dolphin sightings nearshore had proven elusive.
Accelerating, the boat headed west toward the edge of the Continental Shelf, to deeper water. Suddenly, several prominent dorsal fins cut through the waves at a distance, similar to those of the female killer whales that had taken the shark. Excitement mounted; could these be those same killer whales? But soon the captain announced from the wheelhouse, “Risso’s dolphins off the starboard bow!” Disappointment was quickly replaced by fascination: ahead was a rag-tag pod of fifteen pale-to-dark gray dolphins, like crudely modeled clay replicas of the sleek creatures the watchers expected. They sported bulbous white heads, but no rostrum, or beak. Most bore white scars on their chunky bodies. Some wore a quizzical, half-amused smile: and the fun was just beginning. The dolphins abruptly launched into a series of breakneck antics: high leaps, somersaults, pirouettes and tail-slaps. These were the grinning Grampus griseus, aka Risso’s dolphins.
CITIZENS OF THE WORLD: Risso’s dolphins are found throughout the world’s temperate and subtropical seas, but prior to the severe 1982-83 El Nino were uncommon in north-central California waters. They can reach 13 feet, second in size among local dolphins only to killer whales (yes, “orcas” are big dolphins!).
GRAY GHOSTS: Risso’s are dark gray when born, but lighten to a ghostly gray with age and scarring: testament to their rough-and-tumble socializing, and to the sharp beaks and hooks of the squid they dine on. Up to 14 conical teeth erupt from the lower jaw, sufficient to grasp and vacuum up the slippery prey. “Grampus” are gregarious, forming groups of a dozen to over a thousand, sometimes joining Pacific white-sided dolphins and whales. Submarine sorties take them to depths over a thousand feet. Their tall dorsal fins often result in misidentification as killer whales, or large sharks. Aerial acrobats, they’re notoriously boisterous, exuberant; and worth protecting.
GIVING THEM A BREAK: Like all marine mammals, they are protected under the Marine Mammal Protection Act. Neither endangered nor threatened locally, NOAA’s latest (2016) stock assessment for California, Oregon and Washington is 6,336, but can be highly variable. Formerly drowned in large numbers in tropical and offshore waters by the tuna industry’s encircling purse-seine nets, they and other dolphins found safety due to international treaties and regulations arising from activist Sam LaBudde’s heroic undercover film exposing the fishery’s indiscriminate carnage. According to Earth Island Institute, 90% of the tuna industry has now adopted “Dolphin Safe” practices. But threats persist from accidental catch in longline, gillnet and trawl fisheries, and they are vulnerable to contaminants and ocean noise.
NOAA conserves Risso’s and other dolphins through fisheries management, marine sanctuary protections, and research including Applied California Current Ecosystem Studies (ACCESS cruises), a cooperative effort of Greater Farallones and Cordell Bank national marine sanctuaries and Pt. Blue Conservation Science. Together we work to help these righteous and rambunctious dolphins live and thrive.
