Why is my Prefab Instantiating when the Scene is Loaded?

Hello! I am creating a 2D video game where a player can shoot a harpoon when the space bar is pressed, and can move left, right, up, and down using the arrow keys.

When I start my game, the prefab of the harpoon automatically instantiates, although the space bar has not been pressed yet.

Is there something wrong with my code? Do I need to change something in the inspector? What are some other reasons that the prefab instantiates on start? Thanks in advance- George :)

Here is my code-
harpoonScript.cs

 using UnityEngine;
 using System.Collections;
 using UnityEngine.UI;
 
 public class harpoonScript : MonoBehaviour {
 
 // Public variable 
 public int speed = 6;
 private Rigidbody2D r2d;
 public Text FishLabel;
 public int fishKillCount = 0;
 
 // Function called once when the bullet is created
 void Start () {
     // Get the rigidbody component
     r2d = GetComponent<Rigidbody2D>();
 
     // Make the bullet move upward
     float ySpeed = 0;
     float xSpeed = -8;
 
     Vector2 newVelocity = new Vector2(xSpeed, ySpeed);
 r2d.velocity = newVelocity;
 
 }
 
 void OnTriggerEnter2D(Collider2D other) //hero hits side of enemy
     {
         if (r2d = null) {
        Debug.Log("Unable to find GameObject, reference is null");
   } else {
 
              string fishStringfromText = FishLabel.text;
              int fishIntfromText;
              fishIntfromText = int.Parse(fishStringfromText);
 
   ++fishIntfromText;
 
   FishLabel.text = fishIntfromText.ToString();
 
        Debug.Log("GameObject found, reference is not null");
        Destroy(other.gameObject.GetComponent<Collider2D>()); //Remove collider to avoid audio replaying
             other.gameObject.GetComponent<Renderer>().enabled = false; //Make object invisible
             Destroy(other.gameObject, 0.626f); //Destroy object when audio is done playing, destroying it before will cause the audio to stop
     Destroy(GameObject.Find("harpoon_00001(Clone)"));
   }
 
 }
 
 
 }

playerMove.cs

 using UnityEngine;
 using System.Collections;
 
 public class playerMove : MonoBehaviour {
 
     // All Variables
     public float speed = 10;
     private Rigidbody2D rigidBody2D;
     private GameObject harpoon_00001;
     private bool facingRight = true;
 
     void Awake () {
 
         rigidBody2D = GetComponent<Rigidbody2D>();
         harpoon_00001 = GameObject.Find("harpoon_00001");
   if (harpoon_00001 == null) {
        Debug.Log("Unable to find GameObject, reference is null");
   } else {
        Debug.Log("GameObject found, reference is not null");
   }
 
     }
 
 void Update () {
 
     if (Input.GetKeyDown(KeyCode.LeftArrow) && !facingRight) {
         Flip();
     }
 
     if (Input.GetKeyDown(KeyCode.RightArrow) && facingRight) {
         Flip();
     }
 
 }
 
 void Flip () {
 
     facingRight = !facingRight;
 
     Vector3 theScale = transform.localScale;
     theScale.x *= -1;
     transform.localScale = theScale;
 
 }
 
     void FixedUpdate () {
 
         float xMove = Input.GetAxis("Horizontal");
         float yMove = Input.GetAxis("Vertical");
 
         float xSpeed = xMove * speed;
         float ySpeed = yMove * speed;
 
         Vector2 newVelocity = new Vector2(xSpeed, ySpeed);
 
         rigidBody2D.velocity = newVelocity;
 
         if (Input.GetKeyDown("space")) {
             GetComponent<AudioSource>().Play();
             
 harpoonScript harpoon = Instantiate(harpoon_00001,transform.position, Quaternion.identity) as harpoonScript;
 // Assuming harpoon prefab already facing to right
 
 if (facingRight) {
     
 harpoon.transform.eulerAngles = new Vector3(0f, 0f, 180f); // Face backward
   Vector3 theScale = harpoon.transform.localScale;
   theScale.x *= -1;
   harpoon.transform.localScale = theScale; // Flip on y axis
 }
 
 
     }
 
 }
 }