"rock herring" meaning in English

{
  "forms": [
    {
      "form": "rock herrings",
      "tags": [
        "plural"
      ]
    }
  ],
  "head_templates": [
    {
      "args": {},
      "expansion": "rock herring (plural rock herrings)",
      "name": "en-noun"
    }
  ],
  "lang": "English",
  "lang_code": "en",
  "pos": "noun",
  "senses": [
    {
      "categories": [
        {
          "kind": "other",
          "name": "English entries with incorrect language header",
          "parents": [
            "Entries with incorrect language header",
            "Entry maintenance"
          ],
          "source": "w"
        },
        {
          "kind": "other",
          "name": "Pages with 1 entry",
          "parents": [],
          "source": "w"
        },
        {
          "kind": "other",
          "name": "Pages with entries",
          "parents": [],
          "source": "w"
        },
        {
          "kind": "other",
          "name": "Scottish English",
          "parents": [],
          "source": "w"
        },
        {
          "kind": "lifeform",
          "langcode": "en",
          "name": "Herrings",
          "orig": "en:Herrings",
          "parents": [
            "Fish",
            "Otocephalan fish",
            "Vertebrates",
            "Chordates",
            "Animals",
            "Lifeforms",
            "All topics",
            "Life",
            "Fundamental",
            "Nature"
          ],
          "source": "w"
        }
      ],
      "glosses": [
        "Synonym of allis shad"
      ],
      "id": "en-rock_herring-en-noun-SqTaTZ9Z",
      "links": [
        [
          "allis shad",
          "allis shad#English"
        ]
      ],
      "raw_glosses": [
        "(Scotland) Synonym of allis shad"
      ],
      "synonyms": [
        {
          "tags": [
            "synonym",
            "synonym-of"
          ],
          "word": "allis shad"
        }
      ],
      "tags": [
        "Scotland"
      ]
    }
  ],
  "word": "rock herring"
}

{
  "forms": [
    {
      "form": "rock herrings",
      "tags": [
        "plural"
      ]
    }
  ],
  "head_templates": [
    {
      "args": {},
      "expansion": "rock herring (plural rock herrings)",
      "name": "en-noun"
    }
  ],
  "lang": "English",
  "lang_code": "en",
  "pos": "noun",
  "senses": [
    {
      "categories": [
        "English countable nouns",
        "English entries with incorrect language header",
        "English lemmas",
        "English multiword terms",
        "English nouns",
        "Pages with 1 entry",
        "Pages with entries",
        "Scottish English",
        "en:Herrings"
      ],
      "glosses": [
        "Synonym of allis shad"
      ],
      "links": [
        [
          "allis shad",
          "allis shad#English"
        ]
      ],
      "raw_glosses": [
        "(Scotland) Synonym of allis shad"
      ],
      "synonyms": [
        {
          "tags": [
            "synonym",
            "synonym-of"
          ],
          "word": "allis shad"
        }
      ],
      "tags": [
        "Scotland"
      ]
    }
  ],
  "word": "rock herring"
}